Ward Farnsworth - Predator at the Chessboard (Volume 1).pdf

Chapter 1. Introductory Matters.

1.1. A Short Guide to the Site.

Spectacular chess moves produce the same sorts of satisfactions as the climactic moments of other great games: the slam dunk, the thirty-foot putt, the home run. In chess these moves are known as tactics. This web site teaches them in detail. It assumes you know only how the pieces move and builds step-bystep from there. Every idea is illustrated with lots of examples, and every example is explained in plain language that describes a train of thought leading from a problem to its solution. Funny-looking notation is held to a minimum. You can treat each example as a puzzle and try to solve it before reading the explanation, or just read the explanations as you go. The object throughout is to provide a teaching tool that makes the secrets of chess easy for anyone to understand. It's a chess book for people who think they don’t like chess books. (The site also has a new section—the Chess Quizzer—that lets you test your understanding by working on positions chosen at random and with their explanations hidden.) You can start reading anyplace. The rest of this first section gives a fuller account of the idea behind the site and how it differs from existing books; then comes a primer on the most important general principles of tactics: double threats, loose pieces, and forcing moves (if those terms aren't old hat to you, the explanations probably will be useful). Last are some pages discussing further points of interest to some but not others—the notation used in the diagrams, acknowledgments, how to change the look of the font, and other miscellany.

If you want to skip any or all of this first part and plunge into the specific lessons, you can go back to the table of contents (there’s always a link at the upper right corner of the screen) and click on The Knight Fork or whatever other topic sounds appealing. The sections build on each other a bit, but most of them can be enjoyed on their own with no trouble if you prefer to dip in at random or skip parts that get tedious. If you want to navigate through these early parts or any of the other sections more precisely, click on the plus (+) signs in the table of contents to expand each menu. Or click at the top of the contents page to expand all the menus and see the entire structure at once (I recommend this). Or you can flip around by starting anywhere and using the arrows at the bottom of each screen to go page by page. (Clicking on the forward (>) arrow at the lower right corner of this page, for example, will walk you through the rest of this first section.) This site aspires to be the most detailed and systematic treatment of basic chess tactics yet published. It also is meant to be the most congenial to those who like things explained in English. How far it succeeds, and where it might be improved, the reader will judge; I welcome corrections and suggestions, and apologize in advance for the inevitable typos or other glitches (and thank those who have called such mistakes to my attention). All feedback can be sent by way of the link at the bottom center of every page. Let us begin.

1.2. Rationale for the Project. After this introductory part there are five large sections, one for each of the great families of chess tactics: the fork; the discovered attack; the pin and skewer; the removal of the guard; and mating patterns. Within those sections are a total of twenty chapters; within the twenty chapters are nearly two hundred topics. Each topic is illustrated with about a half-dozen positions—occasionally fewer, and sometimes quite a few more.

Why Tactics? If you have played chess at all, you know it is easy for the two sides to trade pieces: your knight takes my bishop, my pawn takes your knight, and we're even. But if your knight takes my bishop and I can’t capture your knight, you gain an edge that probably will be decisive. If one player has more pieces than

the other, he usually wins without much trouble; between good players, a one-piece advantage is enough to cause the disadvantaged party to resign. Thus the most important moments in a chess game generally occur when you take one of your opponent’s pieces and he gets nothing back, or vice versa. So how does it happen that one side takes another side’s pieces for free? Between beginners the common answer is that you wait for your opponent to blunder by leaving a piece unguarded, then you just take it―and hope you aren’t the one to blunder first. Chess games that go this way aren't terribly interesting, and they make it hard to understand what all the fuss over the game is about. The fuss arises because there are moves you can make that force your opponent to cough up pieces unexpectedly. All his men look safe; but then you play a knight fork, a move in which your knight attacks two of his pieces at once. He only has time enough (one turn) to move or protect one of them, so you take the other for free. It's all very satisfying; and it's even better when you first capture his bishop, and he recaptures; then you check his king, and it moves; and then you play the knight fork, winning a piece. What makes this so pleasing is that you've planned the fork and forced your opponent to step into it by playing a few initial moves that forced his replies. These sequences―the little clusters of moves that win your opponent’s pieces―are known, again, as tactics. A tactical sequence generally is a short bunch of moves that wins material (pieces or pawns) or that forces checkmate. Such a sequence also is known as a combination. (Some people quarrel over the distinction between tactics and combinations. We won't.) Now there also are other types of moves you can make in chess that aren't meant to win any pieces. Indeed, during a game you often will have no way to play one of those nifty tactical sequences, so you instead try to improve your position: you put your pieces onto squares where they have more room to move or are aimed at a part of the board where you are trying to put together an attack; or you move

your pieces around to fend off your opponent’s attempts to launch attacks of his own. This sort of play is called strategic. You are working toward general, long-term goals, and perhaps laying the groundwork for a tactical strike of the sort described a moment ago. When you make these sorts of moves you may well not be seeing many moves ahead. You just are arranging your pieces the way you like, and your opponent is doing the same. Since you aren’t making any immediate threats, your opponent is free to go about his business in ways that may be hard for you to predict. Strategy and tactics both are important, but tactics are more important. If you're a whiz at finding clever moves that take your opponent’s pieces, you will be a terrifying opponent, have a good time playing chess, and win lots of games regardless of whether you know a great deal about strategy. If you're a whiz at strategy but not much good at tactics, you will have trouble winning or having fun because your pieces will keep getting taken. You certainly want to know something of strategy; you need ideas about what you can do with your pieces that will create eventual tactical opportunities for them. We will talk about it along the way. The point is just comparative: if you want satisfaction, you had best start by learning how to play tactics―how to spot and execute sequences of moves that allow you to take your opponent’s pieces. What was said about strategy can be said as well about openings. You can spend enormous time mastering the details of an opening―say, the Italian Game or the French Defense. The yield of those efforts, in victories and in fun, probably will be small. You frequently will find that your opponent’s play drags you away from the opening you studied; and even if not, the payoff of a successful opening usually is a minor advantage in position. By itself the advantage will not win you anything or bring you much pleasure. What will bring you immense pleasure, whether or not you know much about openings, is taking your opponent’s pieces. And to do that you need to learn how to use tactics―the weaponry of the chessboard.

All this advice assumes you are not a strong player already. Once the material on this site all is old hat to you, close study of openings and subtler points of strategy will make better sense. One false move in the opening and your goose is cooked if you are playing Garry Kasparov; but this is a site mostly for novices, so if you are reading it you probably should not be planning to play Kasparov anytime soon. You should be planning to play others of at least roughly your own strength ― probably friends who are casual players, or opponents at the local chess club or on the internet. If you keep playing you will move on to better players, but it still will be a long while before a deep study of openings really pays off. In the meantime all of your opponents ― even the strong ones―will give you plenty of tactical opportunities; they will commit oversights that allow you to play pretty combinations and win pieces if you are sharp enough to see the chances for them. Acquiring this sharpness has nothing to do with memorization. It's a skill you gain by learning what clues signal that a combination may be possible, and by studying how to turn those clues into ideas that work.

Its distinctive features can be summarized as follows:

Why Another Book About Them?

This method of organization makes it easier to learn in a systematic way about tactics and the issues that come up in using them. Every idea is shown in several contexts so that it will sink in and the persistent features of the pattern become familiar to you. And the many examples of each complication also will make it easier to recognize patterns during your games: you will start to sense that the position on the board almost resembles a recognizable pattern and almost lends itself to a known tactical theme. Then you can experiment with forcing moves (e.g., checks and captures that require predictable replies from your opponent) to make it work. The idea guides the experimentation. But to have the idea in the first place—to see, for example, that conditions on the board suggest a possible knight fork, even if the exact means of getting there has yet to be worked out—you need a repertoire of known tactical patterns that can be stimulated by the positions you see. The pat-

Since tactics are the most entertaining and important part of chess, it comes as no surprise that there have been many books written about them. This site—which amounts to another book, and not a short one—thus requires a few words of justification. It differs from all the prior work in several important respects. Most books about chess tactics follow one of two patterns. Some describe important tactical ideas—forks, pins, etc.—and explain their logic a bit, then provide perhaps a dozen examples of how each tactic works. The other sort of book presents pages of diagrammed problems for the reader to solve; the answers usually are given in the back with minimal commentary. Both types of books are valuable, especially when used together, but I long have felt there was a place for a different approach. This project attempts to fill the gap.

Many examples, carefully organized. This site goes into greater detail than other books do in explaining each type of tactic and how to overcome the various obstacles that can arise in trying to make it work. There are about 80 knight forks here, for example, and they are broken down according to the different ways the tactic can look when it is lurking two or three moves away on an apparently placid chessboard. It may be that the square your knight needs is guarded but that the guard can be taken; it may be that the piece you want to fork is not very valuable but can be exchanged for a more valuable piece; it may be that you do not yet have a knight fork but that after you check the enemy king a forking possibility will come into view. All of these possibilities, and many others, are illustrated with about a half dozen explanations apiece and sometimes more. The process is repeated for all the major tactical motifs: there are more than 100 queen forks, more than 300 pins, nearly 200 discovered attacks—all subdivided into different ways each of these ideas can look when it is a couple of moves away from perfection.

terns studied here, in all their little variations, are meant to go into the reader's store of visual knowledge and become the basis of useful intuitions and ideas. Trains of thought explained. Chess tactics tend to involve the use of certain root ideas— cognitive riffs—that get repeated and combined in various ways. The explanations here are meant to explain and reinforce those ideas so they become a natural part of your thought process at the board.

This project especially is meant for those who like explanations in words. Not everyone does; some students of chess prefer just diagrams with lists of the moves required to solve them. But I suspect that those who do think best in words will find it helpful—more interesting, easier to understand, and more likely to improve their play—to have the solutions to problems explained out in English. These are matters of taste, and you, gentle reader, may not think the world really needs more words about chess. But if you do share this sense of mine, and have not found that most books about chess explain it in a way that speaks to you or affects your play, perhaps this site will change your relationship to the game.

Here is a slightly larger statement of the point. The quality of your chess is determined by the quality of your train of thought when deciding what move to make. The train of thought may be partly verbal, partly visual, or partly intuitive, but in any case it will involve a sequence in which you consider candidate moves and their pros and cons. The climb from novice to something better largely is a move from meandering, unsystematic trains of thought to more methodical and fruitful ones. For the beginner it therefore is helpful to see more than just a list of the correct moves that solve a chess problem; it helps to hear what questions one might have asked to spot the pattern and discover the correct moves for oneself. Thus every example here is accompanied by commentary explaining not just the right moves but a train of thought that leads from the position to its solution.

If you are new to chess, the sequences that good players use to win games may seem impossibly complicated. But most of them actually are based on just a few general concepts combined ingeniously and persistently. This frame and the ones that follow explain the concepts broadly. The rest of the site teaches their use in detail.

The trains of thought offered in the commentaries emphasize the use of clues: signs to search for during your games that indicate a tactic might be available. The explanations show how the same sets of questions, some of them simple, can generate impressive tactical ideas when they are asked and answered methodically. Some trains of thought thus are repeated many times. The repetition would be inexcusable if the purpose of the project were just to transmit information, for then once would be enough. But the purpose is otherwise; it is to help change your mental habits at the board, and for this purpose an extra measure of clarity and some repetition both are helpful.

The most important idea in chess is the double threat. Generally speaking a double threat is any move you make that presents your opponent with two problems at the same time. Since each player can make just one move per turn, your opponent only has time to address one of the threats you have made. On your next turn you execute the other one. Maybe your first move checks his king and attacks another of his pieces at the same time; or maybe you threaten one of his pieces and are building a threat of checkmate elsewhere. The result is the same: your opponent has to spend his next move dealing with your threat against his king, and then you get to take the other piece you were threatening.

1.3. The Elements of Tactics: A Primer.

1.3.1 The Double Threat.

The universe of chess tactics can be divided into four or five great families of ideas, each of them a variation on the logic of the double threat. This site is organized around them: 1. The first family, and the best-known type of double threat, is the fork — a move where one of your pieces attacks two enemy pieces at the same time. You no doubt have seen examples of knight forks if you have played chess for a while; the knight naturally lends itself to moves in which it attacks two pieces at once. But the same idea can be executed with your queen or with other pieces, as we shall see. 2. A second type of double threat, and another family of tactical ideas, is the discovered attack. This occurs when you move one of your pieces out of the way of another so that both of them make separate attacks against your opponent. Again, he only has time to parry one of the threats. You play out the other one on your next move. 3. A third family of tactical ideas involves the pin or skewer. These occur when two of your opponent’s pieces are on the same line and you place an attacker so that it runs through both of them. In effect you again are making a double threat—one threat against the piece in front and another against the piece behind it. 4. And then there are countless other situations that may be lumped under the heading of removing the guard, in which you capture or harry an enemy piece that guards something else you want to take. Your opponent can’t defend against both threats on the one turn allowed to him, so you are able to play one of them or the other. In effect most games of chess are contests to see who can find a way to use one of those tactical techniques first. One successful fork (or discovery, or skewer, etc.) often decides a game by giving one player an insurmountable advantage over the other. This is why Richard Teichmann said that chess is 99% tactics; and it is why mastery of tactics is the key to having fun at the chessboard, not to mention winning.

[Note: A fifth family of tactical operations involves mating patterns: characteristic ways that kings get trapped. These are treated in the last section of this site. They do not necessarily involve the logic of the double threat in the way that those tactical devices just described do. We also are leaving aside a few other, more minor families of tactics for now.] 1.3.2 The Loose Piece. Another key idea in chess is the loose piece. A loose piece is simply a piece that has no protection. It is common for players to leave pieces unprotected here and there; as long as they aren’t being attacked, they look safe enough. But loose pieces make perfect targets for the double threats described a moment ago. Suppose your queen performs a fork, attacking your opponent’s king and one of his rooks at the same time. He moves his king. Now you can use your queen to take his rook—if it is unprotected. But if the rook is guarded you won’t be able to take it because the cost will be too high: your queen will be captured afterwards. We can turn this point into advice for practical play. You want to be aware of loose pieces on the board at all times. Any piece your opponent has left unguarded is a possible target for a tactical strike; any piece of yours that is left unguarded is a vulnerability. Indeed, you want to not only notice loose enemy pieces but also look for ways to create them. We will see countless examples in the studies to come. ("Loose pieces" also can be defined to include enemy pieces that are underdefended: attacked once and defended once by a fellow piece. As we shall see, pieces in that condition sometimes can make targets just as good as pieces with no protection at all.) The great chess writer Cecil Purdy stated the point as a rule: "Never leave or place a piece loose without first looking for a possible fork or pin, and never see an enemy piece loose without doing the same." Do you follow this advice already? Many inexperienced players don't. When they put a piece onto a new square, they mostly just check to make sure it

won't get taken there. Purdy's advice is different. It is to ask whether your piece has protection on its new square; and if it doesn't, to ask carefully whether a fork or pin or other tactic might be launched against it. You may not yet understand quite what it means to look for forks or pins, but you will soon; and then following Purdy's counsel will save you many sorrows.

1.3.3 The Forcing Move. Sometimes in chess you do whatever you want to do and then your opponent does whatever he wants to do. Other times it’s different: if you capture his knight with your bishop, for example, he pretty much has to recapture your bishop; otherwise he simply is short a piece and probably will lose. (The other pieces belonging to both sides gradually will be exchanged away, and you will end up with the only attacking piece left on the board.) Another example: If you check your opponent’s king, he can’t do whatever he wants in reply; he has to either move the king, block the check, or capture the piece you have used to make the threat. And if you make a move that will enable you to deliver checkmate on your next turn—a “mating threat”—your opponent likewise will have to address it immediately. Checks, captures, and mate threats therefore are known as forcing moves. In other words, they are moves that force your opponent to pick from a small set of possible replies. They are the essence of tactical chess; they allow you to dictate your opponent’s moves and thus control how the board will look two or three or more moves from now. Other types of moves may be "forcing" as well, mind you: any threat you make against your opponent— for example, a simple threat to take one of his pieces on your next move—may force him to reply in a certain way. This happens all the time, and we will see examples as we go. But checks, captures, and mate threats tend to be the most interesting and important kind of

forcing moves because they so powerfully limit your opponent's choice of replies. This notion of forcing moves helps clear up some common confusions about chess. No doubt you have heard about good players seeing ahead five moves, or a dozen moves, or more; how do they do that when their opponents have so many possible responses to pick from? The usual answer is that their opponents don’t have so many choices after all. Suppose I think like this: if I take your knight with my bishop, you will have to recapture my bishop; then if I check your king, you will have to move it over one square; then if I check your king on its new square, you will have to block my check; then your rook will be left loose and I will take it. In this case I have seen ahead four moves, but notice that I didn’t have to keep track of a lot of possible variations. To each of my moves you only had one plausible reply. I just had to realize this. Of course sometimes your opponent will have more than one plausible reply, and in that case you will need to keep track of some variations after all (“if he does this, I’ll do that; if he does the other thing, then I go to plan B,” etc.). And it’s true that very strong players can keep straight lots of variations. But it’s also true that a lot of great tactical sequences consist entirely of forced moves that make it not so hard to see ahead. Once you grasp the idea of forcing moves it also is easier to understand how to come up with nifty tactical ideas during your games. Of course you might like to unleash a fork or discovery or skewer, but what if no such moves are possible when it’s your turn? Do you wait around for a fork to become available? No; your first job when you are deciding what move to play is to examine your possible forcing moves: any checks, captures, or mating threats you can offer. You don't look at these things just as ends in themselves; you ask what moves your opponent would be forced to make in reply, and whether you then would be able to play a fork or discovery or skewer or some other tactic. If the answer is no, you imagine playing another forcing move after the first one and then ask the same questions.

The point of experimenting with forcing moves, in short, is that they change the look of the board. They may open up lines that currently are cluttered; they may cause your opponent to leave pieces loose that now have protection; they may make him line up pieces that are not now on the same line; they may make him put his king where it can be checked. Your task is to imagine the board as it would look after your forcing moves and see if changes such as those would create tactical openings for you. Gradually a pattern you recognize may emerge—the makings of a fork or discovery or other idea. With practice this becomes second nature: if your rook is aimed at your opponent’s knight, you automatically consider capturing the knight and allowing your rook to be taken. This would be a sacrifice, of course, since rooks are more valuable than knights, but great tactical ideas routinely begin with sacrifices like that. The question is whether the exchange of your rook for his knight would leave you with a chance to play a fork or other double threat—or with a chance to play another forcing move that isn’t yet possible. Maybe after your rook is captured you then can play a check that wasn’t available before; and maybe after your opponent responds to the check you then will have a fork. But it all starts by thinking about a simple capture you can make and its consequences. Likewise, you generally don’t want to make any moves without being aware of any checks you give and their consequences. Checks are the most forcing moves of all because your opponent is required to reply by moving his king, taking the piece that threatens it, or moving a piece between them. This usually makes it easy to see what a check will require your opponent to do. And since a check often forces your opponent to move his king, it may lead directly to tactics that make the king a target—a fork with the king at one end, or a pin with a king at the rear, or for that matter checkmate. Looking at any checks and captures you have to offer is like looking for loose pieces on the board: these are things you do all the time

during a game, because most great tactical ideas involve one of those elements or the other. 1.3.4 Strategy vs. Tactics. Often you will look at your forcing moves and decide they lead nowhere. That’s fine; now you instead play a strategic move rather than a tactical one—a move that improves the quality of your position without trying directly to win your opponent’s pieces or mate his king. But strategy and tactics are linked, since one goal of strategic, “positional” play is to increase the power of your pieces and create fertile conditions for tactical strikes on later moves. Sometimes this is a matter of arranging your pieces so that they have more freedom of movement and denying the same freedoms to your opponent; sometimes it is a matter of coordinating your pieces so that they are aimed at the same sector of the board; sometimes it is a matter of arranging your pawns to help achieve those same purposes for your pieces. At the end of our study of each tactical family (and sometimes more often), we will pause to consider its strategic implications: what the tactical ideas teach about the right sorts of moves to play when there is no such tactic yet available. All this talk of weaponry admittedly is abstract. It will become concrete in the studies that follow. We will look at over a thousand tactical sequences. The rough structure of most of these sequences, and of a large share of all the great tactical moves ever played in chess, is similar; it involves the elements just described. First there are some forcing moves—checks or captures or mating threats that limit your opponent’s replies. Then there is a denouement: a double threat, such as a fork or discovered attack or one of the other themes we will consider, that becomes possible after the forcing moves have changed the board. As a result you are able to take a loose or underprotected enemy piece. We can call this a combination. The variations on this pattern are limitless, and there is much to know about its details: how to spot forcing moves and figure out their consequences, and how to spot the patterns suggesting that a fork

or pin is in order. You can spend a lifetime building your understanding of those things and gaining skill at carrying them out under time pressure. But as you get started it all may be more manageable if you consider these studies as variations on the single idea just described. The rest of this introductory section will be discussing chess notation and jargon, then some more technical aspects of the site. This therefore is a good time for a reminder that if you want to skip any or all of that stuff, perhaps because you already are comfortable reading about chess positions and want to cut right to some lessons, you can go back to the table of contents and navigate from there by using the link near the upper right corner of this screen.

1.4 Notation; Jargon; the Look of the Site; Hard Copies.

1.4.1. Notation and Jargon. This site makes every effort to explain everything in words, but when describing a series of chess moves it often is convenient to use abbreviations to describe them. Those abbreviations are known in chess as notation. This site generally uses the “algebraic” notation employed in most chess books, though with a small difference explained below. Despite the unpleasant label, it's very easy to understand. Most of it can be figured out as you read, but here is what you need to know about how it works: 1. Squares are named by their coordinates— a4, e5, h8, etc.; these should be self explanatory, since every diagram includes numbers running up the side of the board and letters along the bottom. The numbered horizontal rows are called ranks. The vertical columns named by letters are called files. 2. Pieces are named by their first letter. Q = queen; R = rook; etc. The only exception is the knight, which is referred to as “N” to dis-

tinguish it from the King (“K”). Pawns are named by their squares, so that “d4-d5” means the pawn on d4 moves to d5. Sometimes in this book (and routinely in other books) a pawn move is described without bothering to name the square it came from: one simply says "1. d5," and everyone understands this means that the pawn on the d-file moves to d5. 3. Captures are described with an “x” between the names of the pieces capturing and being captured. So QxB means queen takes bishop; Rxa5 means the rook captures the pawn on a5; and h7xN means the pawn on h7 captures the opposing knight. This last point is the way that the notation here varies from the usual algebraic notation in other books. Algebraic notation normally describes a capture by just referring to the square where it occurs. Thus if White’s queen takes Black’s rook on the f6 square, most chess books would say “Qxf6”; but on this site we will say “QxR.” The reason for the difference is that this site is meant primarily for people who haven’t read other chess books before (as noted before, it's a chess book for people who don't like chess books), and for that audience the notation used here will be more intuitive. It's easy to understand that “QxB” means “queen takes bishop”: easy to imagine, and easy to find on the board. “Qxf6,” however, has to be translated into “queen takes bishop” by looking at the board, finding f6, and seeing what piece is there. That’s easy when you know instinctively where f6 is, but most readers of this project probably will find it faster to locate the bishop than to locate f6. The real benefits of naming captures by the squares where they occur come when describing long sequences, and few of the sequences here will be all that long. (The approach used here is similar to the one used in Bobby Fischer Teaches Chess, a well-executed book for beginners.) This approach to describing captures should be easy to follow for readers already used to ordinary algebraic notation; anyone can understand what QxB means even if they are used to reading Qxf6. The gripe I anticipate

from those who get worked up about these things is that if readers become used to this approach they will find it hard to read algebraic notation in other books: they will see, say, “Qxf6” elsewhere and have trouble remembering that the other author means to say the queen captures whatever piece is on f6, not that the queen captures the f6 pawn (as it will mean here). I regard this as a trivial complaint; the reader of this site who does move on to other books should have no trouble making the transition if the above explanation is kept in mind (or just figuring it out on the fly; for this explanation makes the whole business sound more confusing than it is in practice). It's not that big a deal. 4. Turning back to the notation rules, castling is indicated by writing 0-0 (if it's on the side of the board where the king starts) or 0-0-0 (if it's on the queenside: long castling, as it is called). 5. Now a couple of minor points that don't come up often; you probably don't need to worry about them, but for the sake of completeness: if a capture is made en passant, that's indicated by writing "ep" afterwards or some variant. (I'm assuming you know what an en passant capture is, but if you don't, I'll explain it if it ever gets used here—and in the meantime you easily can find an explanation of it elsewhere on the web.) Second, if one of your pawns reaches the opponent's back rank, it gets promoted to some other more powerful piece of your choice—usually the queen, though very occasionally some other choice works better. We indicate promotion with an equal sign: f7-f8=Q means the pawn on f7 moves to f8 and becomes a queen. Again, I'll say more about this wherever it pops up. Finally, if more than one piece could be indicated by a description (in other words, if I refer to "R" but there are two rooks on the board and it's not obvious which one is meant), sometimes the coordinate of the piece will be given as well. So Rc8xN means the rook on c8 (not some other rook) captures the opponent's knight. Occasionally this approach also will be used just for clarity's sake even if there is no technical reason for confusion.

6. Sequences of moves are described in pairs, with the White move first. Thus a game might begin 1. e2-e4, e7-e5 [again, this could have been written "1. e4, e5"]; 2. Nf3, Nc6; 3. Bb5, a7-a6; 4. BxN, d7xB. This means that White started by moving his e-pawn forward two squares, and that Black then did the same; then on White’s second turn he moved his knight to f3, and then Black moved his knight to c6. White brought out his bishop. Black chased it with his pawn on the a-file. White replied by taking Black's knight. Black recaptured with pawn on c6. The position on the left illustrates the result. When we look at positions from the middle of a game (as we generally will) we will describe White’s first move in that position with the numeral “1” (as something like “1. Nf5,” for example). We call it “1” because it’s the first move in the pictured position, even though it’s not the first move in the game. If we want to start by describing a move of Black’s, we do it by saying something like: “Black can play 1. …Nf5.” The “1” followed by the three dots indicates that we’re looking at the first pair of moves in the position but that we’re starting with the second half of the pair: in other words, with Black’s move. 7. A plus sign after a move (like this: Rh8+) means that the move checks the enemy king. A "#" sign after a move (like this: Rh8#) means that the move is checkmate (or simply “mate,” as we more commonly say). 8. It often happens that a player can sacrifice a knight or bishop to win an enemy rook. Since rooks are more valuable than knights or bishops, a player who does this is said to have “won the exchange.” If we reach a stage of the game where I have, say, a bishop and a rook and you have a bishop and a knight, I am said to be “ahead the exchange.” 9. A piece is said to be “loose” if it has no defenders. It is “hanging” if it is exposed to capture; you hang your queen if you leave it where your opponent can take it for free. This also is known as leaving a piece en prise.

1.4.2. The Value of the Pieces. This site assumes that you know how to play chess—in other words, how the pieces move. If you know that much, you probably also know which pieces are worth more than which. But to be on the safe side, it is conventional to rank the pieces in the following order of value, with points given to them as indicated to make it easier to work out whether a set of exchanges is favorable or unfavorable:

If you use Mozilla’s Firefox browser, you likewise can fiddle with Tools …Options …Fonts & Colors. Check "Always use my fonts"; then set your preferred font elsewhere in that same window. The Microsoft browser produces slightly better results for some people (sorry!), but it may depend on what sort of monitor you use. If none of this helps, please let me know. I'm still working on making the type easy to read on every computer screen.

Queen = 9 Rook = 5 1.4.4. About the Dinosaurs. Bishop = 3 Knight = 3 Pawn = 1

1.4.3. Making the Site Easier to Read. First of all, the site is best viewed at a resolution of at least 1024 x 768. Anything smaller will force you to use a slider bar to read the pages: no fun at all. My apologies to those who don't have such an option, but the majority of all monitors nowadays can achieve this, and it makes for the best reading environment. If the size of the type on this site, or the spaces between the lines, aren’t to your liking, you should be able to adjust them in the usual way (hit CTRL and then use the scroll button on your mouse; or use the “View” menu on your browser). If you are having trouble getting satisfactory results this way, you may find it useful to disable the site’s automatic formatting. On Microsoft’s Internet Explorer you do this by going to Tools… Internet Options… Accessibility… and then checking the boxes to ignore the font styles or sizes (or both) specified on web pages. Then set your own font (still on the Internet Options page) and play again with the browser’s type size settings (under the View menu).

This site is titled Predator at the Chessboard, and is decorated with dinosaurs; yet the dinosaurs pictured are herbivores. Is this not a contradiction of some sort? In fact it isn't; and this, patient reader, for two reasons. First, if you unexpectedly were to encounter a Stegosaurus or a Triceratops—such as, perhaps, the handsome one shown to the left— you yourself would regard it as a decidedly formidable predator, would you not? But second and more to the point, the complaint about the dining habits of the pictured dinosaurs reflects, I say, a failure of perspective and imagination; for you too hastily are assuming that they are the predators. Has it occurred to you that they are the prey, and that you are the Tyrannosaurus (or, perhaps, the Allosaurus) intending to dine on them? That is the sort of thinking this site means to encourage. After reading it for a while, situations that formerly caused you to react with dread and an instinct for defense and retreat will instead inspire you to think by habit— aye, and with relish—about making a meal of your opponent. Either that, or plants make underrated prey; but Herbivore at the Chessboard didn't have the same ring to it. Onward.

1.4.5. Hard Copies. Many readers of the site have written to ask if the material it contains is available in hard copy. Now it is; there are links at top of the front page. These are oversized paperbacks, and they contain every position and discussion that appears in the online version: over 700 pages in total, with over 1,000 illustrations and commentaries. I hope they will be a convenience to those who prefer reading books to reading screens. Hardcover versions are available, too; you can find them by searching at www.lulu.com, which is where the links on the front page will take you anyway. At the lower left of the publisher's site, you can ask to have the prices displayed in pounds or euros if you prefer.

Second—in alphabetical order only—is Tim Feinstein, a wonderful chessplayer and terrific lawyer who read the manuscript. He caught many mistakes and made a lot of great suggestions. (Many errors no doubt remain here and there. He isn’t responsible for them.) Tim is a generous teacher from whom I have learned much about the game, and I thank him profusely. In everyday life he is far kinder than he appears in this picture, which captures him in a moment of characteristic brutality toward an opponent. You wouldn't want to cross him at the chessboard.

1.5 Acknowledgments and Bibliography.

I now wish to thank two gentlemen, each of whom has lent a bit of his genius to this project. The first is Alon Cohen, the builder of this site, pictured to the left. He is a man of surpassing energy, generosity, and creativity, and I hope you will share my judgment that he has done a beautiful as well as a functional job. We collaborated on the design; anything you don’t like about it safely can be blamed on me, while the good parts almost certainly were his idea.

Tim Feinstein

Bibliography. One of the goals of this project is to take every problem that commonly arises in tactical play and illustrate its handling with a half dozen or so progressive illustrations. To find the positions needed for the purpose—roughly 1,200 in all—I drew on just about every source I could find. I list them below, and thank their authors (and beg the pardon of any I may have neglected to mention). I have learned from all of them. There are a few notes at the end about some particular titles. Alburt, Chess Training Pocket Book (1997) Ault, The Chess Tutor (1975) Bain, Chess Tactics for Students (1993)

Alon Cohen

Blokh, The Art of Combination (1994)

Blokh, Combinational Motifs (1998)

Lein and Archangelsky, Sharpen Your Tactics! (1996)

Blokh, 600 Combinations (2001) Littlewood, Chess Tactics (1984) Burgess, The Mammoth Book of Chess (1997) Livshitz, Test Your Chess IQ (1981) Chandler, How to Beat Your Dad at Chess (1998) Chernev, Combinations: The Heart of Chess (1960) Chernev, Logical Chess: Move by Move (1957)

Neishtadt, Test Your Tactical Ability (1981) Neishtadt, Your Move! (1990) Palatnik and Alburt, Chess Tactics for the Tournament Player (1995) Polgar, Chess (1994)

Chernev and Reinfeld, Winning Chess (1948) Pongo, Tactical Targets in Chess (2000) Emms, The Ultimate Chess Puzzle Book (2000) Fischer et al., Bobby Fischer Teaches Chess (1966)

Purdy, The Search for Chess Perfection (1997) Reinfeld, 1001 Brilliant Ways to Checkmate (1955)

Furst, Theme Artistry (1987) Gillam, Winning At Chess (1994) Gillam, Your Move (1994) Harding, Better Chess for Average Players (1996) Hays, Combination Challenge (1991) Hays, Winning Chess Tactics for Juniors (1994) Horowitz, How to Win in the Chess Openings (1951)

Reinfeld, 1001 Winning Chess Sacrifices and Combinations (1955) Renaud and Kahn, The Art of the Checkmate (1953) Robertie, Winning Chess Tactics (1996) Seirawan and Silman, Winning Chess Tactics (1995) Tal, Tal-Botvinnik 1960 (1970) Vukovic, Art of Attack in Chess (1998 ed.) Walker, Chess Combinations (1999)

Horowitz and Reinfeld, First Book of Chess (1952) Ivaschenko, The Manual of Chess Combinations (1997) Koltanowski and Finkelstein, Checkmate! (1998) Koltanowski and Finkelstein, Checkmate Strategies (1999)

Weeramantry, Best Lessons of a Chess Coach (1993) Wilson and Albertson, 303 Tricky Chess Tactics (1999) Znosko-Borovsky, The Art of Chess Combination (1959)

Some positions also have appeared in Shelby Lyman’s chess column in the Boston Globe or in Riga’s Chess magazine. A few notes on these: 1. The books by Reinfeld and Hays probably are the best collections of positions to solve if you are looking for practice (a number of positions from those books are discussed here); Livshitz and Gillam also are excellent for that purpose, as is the book by Lein and Archangelsky. 2. Among books that offer instruction in words, I suggest Chernev and Reinfeld's Winning Chess, Ault's The Chess Tutor, and Seirawan and Silman's Winning Chess Tactics. (The first two may be hard to find, but are worth the trouble.) Many of the others are excellent, too, and I don't mean to slight any of them by mentioning these three. Of course those books fill a somewhat similar niche to this site; for those who are reading this, they are my competition. But I encourage you to check them out and make comparisons. Different people learn better from different writers. 3. The titles by Renaud and Kahn and by Chandler are terrific sources on mating patterns; so are the Koltanowski and Finkelstein books, which are overlooked. Again, many positions in the "mating patterns" section of this site are drawn from those sources. 4. For the reader looking to move on to the study of strategy, I especially recommend Chernev's Logical Chess and Nunn's Understanding Chess, both of which walk you through chess games and explain the strategic (as well as tactical) thinking behind the moves. My other favorite titles on strategy are Jeremy Silman's The Amateur's Mind, How to Reassess Your Chess, and (perhaps most useful of all) The Reassess Your Chess Workbook, which is full of excellent examples and discussion. Seirawan and Silman's Winning Chess Strategies is another fine overview you may find helpful. Everyone's Second Chess Book by Dan Heisman also has a wealth of tips on strategy as well as other topics; Heis-

man offers a number of good online resources as well. 5. And for the reader simply looking for good, lively writing about chess, I suggest checking out any of the writings of C.J.S. Purdy, starting with the one referenced above. He is magnificent.

1.6 Chess in Literature. Some Interesting Allusions to Chess. Fielding, Joseph Andrews (1742): But human life, as hath been discovered by some great man or other (for I would by no means be understood to affect the honour of making any such discovery), very much resembles a game at chess; for as in the latter, while a gamester is too attentive to secure himself very strongly on one side the board, he is apt to leave an unguarded opening on the other; so doth it often happen in life, and so did it happen on this occasion; for whilst the cautious constable with such wonderful sagacity had possessed himself of the door, he most unhappily forgot the window. Fielding, Life of Jonathan Wild the Great (1743): How impossible for human prudence to foresee and guard against every circumvention! It is even as a game of chess, where, while the rook, or knight, or bishop, is busied forecasting some great enterprize, a worthless pawn exposes and disconcerts his scheme. Boswell, Life of Johnson (1791): There is one circumstance in Sir John's character of Bishop Still, which is peculiarly applicable to Johnson: “He became so famous a disputer, that the learnedest were even afraid to dispute with him; and he finding his own strength, could not stick to warn them in their arguments to take heed to their answers, like a perfect fencer that will tell aforehand in which button he will give the venew, or like a cunning chess-player that will appoint aforehand

with which pawn and in what place he will give the mate.” Dickens, Bleak House (1853): He is clear that every such person wants to depose him. If he be ever asked how, why, when, or wherefore, he shuts up one eye and shakes his head. On the strength of these profound views, he in the most ingenious manner takes infinite pains to counterplot when there is no plot, and plays the deepest games of chess without any adversary.

sane, but extremely business-like; and if Shakespeare ever really held horses, it was because he was much the safest man to hold them. Imagination does not breed insanity. Exactly what does breed insanity is reason. Poets do not go mad; but chess-players do. Stoker, Dracula (1897): So be it that he has gone elsewhere. Good! It has given us opportunity to cry 'check' in some ways in this chess game, which we play for the stake of human souls.

James, The Figure in the Carpet (1896):

Orwell, Homage to Catalonia (1938):

The figures on the chessboard were still the passions and jealousies and superstitions and stupidities of man, and their position with regard to each other, at any given moment, could be of interest only to the grim, invisible fates who played the game – who sat, through the ages, bow-backed over the table.

What purpose is served by saying that men like Maxton are in Fascist pay? Only the purpose of making serious discussion impossible. It is as though in the middle of a chess tournament one competitor should suddenly begin screaming that the other is guilty of arson or bigamy. The point that is really at issue remains untouched.

Churchill, The People’s Rights (1909): Moves are made upon the scientific and strategic boards, advantages are gained by mechanical means, as a result of which scores of millions of men become incapable of further resistance, or judge themselves incapable of further resistance, and a fearful game of chess proceeds from check to mate by which the unhappy players seem to be inexorably bound. Roosevelt, The Conditions of Success (1910): There are exceptional cases, of course, where there is a man who can do just one thing, such as a man who can play a dozen games of chess or juggle with four rows of figures at once—and as a rule he can do nothing else. Chesterton, The Maniac (1908): Poets are commonly spoken of as psychologically unreliable; and generally there is a vague association between wreathing laurels in your hair and sticking straws in it. Facts and history utterly contradict this view. Most of the very great poets have been not only

Oliver Wendell Holmes, Sr., The Autocrat of the Breakfast Table (1858): The whole force of conversation depends on how much you can take for granted. Vulgar chess-players have to play their game out; nothing short of the brutality of an actual checkmate satisfies their dull apprehensions. But look at two masters of that noble game! White stands well enough, so far as you can see; but Red says, Mate in six moves;—White looks,—nods;—the game is over. Just so in talking with first-rate men; especially when they are good-natured and expansive, as they are apt to be at table. Oliver Wendell Holmes, Sr., The Poet at the Breakfast Table (1872): Men's minds are like the pieces on a chessboard in their way of moving. One mind creeps from the square it is on to the next, straight forward, like the pawns. Another sticks close to its own line of thought and follows it as far as it goes, with no heed for others' opinions, as the bishop sweeps the board in the line of his own color. And an-

other class of minds break through everything that lies before them, ride over argument and opposition, and go to the end of the board, like the castle. But there is still another sort of intellect which is very apt to jump over the thought that stands next and come down in the unexpected way of the knight. But that same knight, as the chess manuals will show you, will contrive to get on to every square of the board in a pretty series of moves that looks like a pattern of embroidery, and so these zigzagging minds like the Master's, and I suppose my own is something like it, will sooner or later get back to the square next the one they started from.

solitaire with the members of your own family for pegs, if you like, and if none of them rebel. You can play checkers with a little community of meek, like-minded people. But when it comes to the handling of a great state, you will find that nature has emptied a box of chessmen before you, and you must play with them so as to give each its proper move, or sweep them off the board, and come back to the homely game such as I used to see played with beans and kernels of corn on squares marked upon the back of the kitchen bellows.

Oliver Wendell Holmes, Sr., Ralph Waldo Emerson (1891):

We often move to the objects of supreme curiosity or desire, not in the lines of castle or bishop on the chess-board, but with the knight's zigzag, at first in the wrong direction, making believe to ourselves we are not after the thing coveted.

Inherited qualities move along their several paths not unlike the pieces in the game of chess. Sometimes the character of the son can be traced directly to that of the father or of the mother, as the pawn's move carries him from one square to the next. Sometimes a series of distinguished fathers follows in a line, or a succession of superior mothers, as the black or white bishop sweeps the board on his own color. Sometimes the distinguishing characters pass from one sex to the other indifferently, as the castle strides over the black and white squares. Sometimes an uncle or aunt lives over again in a nephew or niece, as if the knight's move were repeated on the squares of human individuality. It is not impossible, then, that some of the qualities we mark in Emerson may have come from the remote ancestor whose name figures with distinction in the early history of New England. Oliver Wendell Holmes, Sr., Over the Teacups (1890): Life is a very different sort of game. It is a game of chess, and not of solitaire, nor even of checkers. The men are not all pawns, but you have your knights, bishops, rooks,—yes, your king and queen,—to be provided for. Not with these names, of course, but all looking for their proper places, and having their own laws and modes of action. You can play

Oliver Wendell Holmes, Sr., The Guardian Angel (1867):

Oliver Wendell Holmes, Sr., The Guardian Angel (1867): With most men life is like backgammon, half skill, and half luck, but with him it was like chess. He never pushed a pawn without reckoning the cost, and when his mind was least busy it was sure to be half a dozen moves ahead of the game as it was standing.

Chapter 2: The Double Attack.

2.1. The Knight Fork. 2.1.1 Introduction.

Dg001: Black to move Dg001: We begin our study of tactics with double attacks, or forks: moves that attack two enemy targets at once. And we begin our study of double attacks with knight forks. In the skeletal diagram to the left, White’s knight has forked Black’s king and rook; in other words, it attacks them at the same time. Why start with the knight? Because it is an especially vicious and common forking tool. First, it can threaten a wide range of targets. The knight is roughly comparable in value to a bishop, and so is less valuable than a rook or queen; thus a knight not only can attack any unprotected (or “loose”) enemy pieces but also can be exchanged favorably for enemy queens and rooks regardless of whether they have protection. Second, the knight’s unique, non-straight pattern of movement creates two advantages: it allows a knight to attack other pieces without fear of being captured by them; and it enables a knight to make jumps and deliver threats that are surprising to the eye and so are easy to overlook. To spot possible knight forks you will want to become habitually aware of the relationships between your knights and your opponent’s pieces (and between his knights and your pieces), especially as the knight progresses up the board. Every rank a knight moves forward tends to bring it closer to forking targets, especially the king; notice that once your knight

reaches its fourth rank, it can attack your opponent’s back rank, and often his king, in one move (thus in the diagram to the left, White’s knight might have been on e4 a move earlier—seemingly pretty far from Black's king). Hence the strategic importance of planting knights on central and advanced squares, and the tactical importance of constantly looking for forks your knight might be able to deliver once it is properly developed. The difficulty in fashioning a fork, of course, is that no matter where your knight sits you rarely will find a fork lying one move away against a decent player. Leaving two pieces to be forked by a knight on the next move is a blunder almost as bad as leaving a piece hanging outright. Forks have to be manufactured; the challenge is to see when one lies a few steps away. Fortunately knight forks a few steps away come in a finite number of types that you can learn to search for systematically and, with practice, recognize quickly. Such situations can be sorted into two general types.

Dg002: White to move Dg002: First, sometimes two of your opponent’s pieces sit on squares that can be forked with one move of your knight, but there is some obstacle to your taking advantage of this; most commonly, the square your knight needs to reach—call it the “forking square”— is defended by your opponent (the diagram to the left shows such a case, again in skeletal form; White would like to play the fork Nf6+, but he can't; the f6 square is defended by a pawn). We will refer to these as cases where you have a potential fork—a move that amounts to a fork on its face, but that needs to

be perfected by overcoming some defensive measure that your opponent has in place. In a moment we will catalogue those defensive measures and how to deal with them.

Dg003: White to move Dg003: Second, sometimes you will not have even a potential fork because your opponent’s pieces are not arranged for it; there are no two enemy pieces that your knight can attack in one move. Thus in the diagram to the left, White cannot deliver a fork, but he could if he were able to get Black’s king to move over a square onto g8. In cases like this it sometimes is possible to draw enemy pieces onto forkable squares with some forcing moves—most often with a check or two. Later we will consider the clues that such possibilities for manipulation may exist and how they can be brought to fruition.

2.1.2. Seeing Potential Forks.

Dg004: White to move Dg004: Let's begin with ways of perfecting potential forks—in other words, cases where your opponent starts with two pieces that at

least are on forkable squares. The first important thing is to see all such forks in the first place. It helps to start by learning to spot all of a knight’s possible moves at a glance. For this purpose you will want a clear mental picture of the ring of eight squares that are the maximum to which a well-placed knight can move. In the diagram on the left, the White circles show squares where the White knight can jump, and the Black circles show squares where the horribly positioned Black knight can jump. Now you can understand why having your knight near the edge of the board generally is bad policy: it can’t reach—and thus can’t control—many squares from there. Study these visual patterns so that seeing a knight’s moves from any position comes easily to you.

Dg005: Black to move Dg005: Now to the matter of spotting knight forks in particular. You may be used to certain forking patterns: your opponent’s king and rook are a square apart on his back rank, inviting you to fork them. But it takes more care never to overlook a potential fork when the board is crowded and the pieces to be forked are not lined up so neatly on the same row. Consider the opportunities here for Black’s knight on b7. By moving to c5 it can fork four White pieces (find them); by moving to d6 it can fork two pieces. Whether either of these forks "work" is another question (the squares the knights need are guarded, though Black has possible replies, etc.), but don't worry about that now. It's just an exercise in geometry: we want to see everyplace where two White pieces are in a forkable position. Seeing only the obvious forking candidates is no good, and won’t lead to tactical magic. If they

are obvious your opponent can see them, too, and can avoid them. You want to see all of the possibilities every time they exist. Notice an important feature of the knight's movements: every time a knight moves it lands on a different colored square. This can be used to make your searching more efficient. It means that two pieces can be forked by a knight only if they are on squares of the same color; it means that they only can be forked by a knight that lands on a square of the opposite color; and it therefore means that if a knight is in position to deliver a fork on its next move, the knight and its targets must all then be sitting on squares of the same color. This is a valuable idea; consider it a law of knight forks. To state the practical implication plainly, one way to build your ability to see all the potential knight forks on the board is to look for any two pieces of your opponent’s that are on squares of the same color as the square where your knight sits. If, as in this case, your knight is on a light square, scan the board for pieces of your opponent’s also on light squares. Can any two of them be forked by your knight? This only takes a moment; you aren’t yet analyzing whether any of the forks would work, but just are reviewing the board visually for simple patterns—a color scan. Sometimes this will be a helpful way to alert yourself to forking opportunities; in other positions it will be more efficient just to look directly at your knight moves without reference to square color. Experiment.

Dg006: White to move

Dg006: As you do your scanning you will discover certain additional laws of knight moves that will become part of your visual vocabulary. An important example is that two pieces can't be forked if they are on the same diagonal with one square between them. Thus the Black king and queen in the diagram to the left are on squares of the same color, but there is no square from which a knight would be able to attack them both. This is a familiar pattern, and when you see it you will not need to pause to think about whether a knight fork is in the immediate offing; the sight of it will be self-explanatory, and you will move on. Similarly, if your knight is on the same diagonal as an enemy piece and separated from it by one square, the knight is three moves away from being able to attack the piece. Thus in the diagram the White knight is three moves from being able to attack the Black king; it must move, say, to e4, then to g5, then to e6. Another useful thing to know is that a knight may be able to attack an enemy target two different ways—but never more than two. In the diagram, for example, White's knight can attack the Black rook by moving to e4 or d5 (and only the latter move creates a fork). This is useful to remember because the first attacking idea you see with your knight may turn out not to be the best one—even against the same enemy piece. Practice broad-mindedness when you scan for forking prospects. It is especially important not to dismiss a possible fork automatically, perhaps half-consciously, when you notice that the square your knight needs is protected by a pawn, or when you see that the fork would involve your opponent’s king on the one hand but a knight or protected pawn on the other. In the latter case you might quickly imagine that if you tried the fork the enemy would move his king and the pawn would not be worth taking, and so write off the forking prospect without taking it seriously. But that train of thought is premature; great combinations often look just that way at first. You want to separate the creative process of seeing that the geometry is there for a fork from the

editing process of analyzing whether the fork can be made profitable. Much of the rest of this chapter is devoted to the editing process: how to take potential forks that look defective and turn them into tactical shots that work. But all along you also want to build the visual habit of noticing every time your knight can attack two sensitive points at once, no matter how implausible the attack looks at first.

2.1.3. The Pinned Guard. When you see a possible knight fork, a natural first question is whether the square your knight needs is protected by any of your opponent’s pieces. If it is, your attention turns to the guard of the square and whether you can get rid of it—or whether you really need to get rid of it. Perhaps you don't; maybe the protection that the piece appears to offer is an illusion, as is the case if the guard is pinned. A piece is pinned if it can't move without exposing the king or another valuable piece to attack. Indeed, a piece that screens its own king from attack is subject to an “absolute” pin and so cannot legally move. We will study pins in detail in later chapters, but this much is enough to help you see that sometimes a square that looks well-defended really isn't.

Dg007: Black to move Dg007: So here is our method in this section: consider the piece that protects the square you want to occupy—we can call it the guard of the forking square—and see what other pieces may be on the same line with it and thus exposed to attack if it moves. Start with the diagram. There is a knight fork waiting for Black

with Nf2; the placement of White's king and queen with three squares between them on the first rank is a classic setup for a double attack. If that isn't yet obvious to you, notice that your knight is on a light square and that White's king and queen (not to mention several other pieces) are on light squares as well, which encourages a look at whether you can fork any of them. Having found Nf2 one way or another, ask: is f2 protected? It seems to be, by the White rook at f3; so study the rook more carefully. It's on the same line with its king, and with your queen. This means that if the rook moves it will expose its king to attack—which is to say that the rook can't legally move at all. So Nf2+ can be played with impunity, and it wins the queen after White moves his king.

Dg008: White to move Dg008: Our modus operandi is to look for double attacks with the knight and ask whether they can be made to work. This time you're playing the White pieces. Notice first here that your knight is on a dark square; now look for Black pieces also on dark squares. You find the Black rook and king, and ask whether they can be forked. They can, with Nd5+. Now ask: Is d5 protected? Yes, by the pawn at c6. But before worrying further you examine the pawn to see if it is constrained. It is; it’s pinned to the king by the White rook at a6. So Nd5+ is safe, and it forks and wins the Black rook. This position is structurally about the same as the previous one. Dg009: White’s most advanced knight (generally the one you want to examine first) is on a light square. Again you might just look for knight moves, or you might look for forking

candidates by scanning for Black pieces also on light squares, and find many—both of his knights, one of his bishops, one of his rooks, and his king.

sequence. His bishop back on g5 now is attacked twice and defended only once. Does he lose it? No—but only because once his knight ends up on b7, it attacks Black’s queen. Now if Black plays BxB, White has NxQ. Black therefore needs to spend his next move taking his queen out of danger, and White’s fork works after all. The general lesson: be mindful of the defensive work your pieces are doing before you send them off to attack.

Dg009: White to move Nd6+ forks Black’s king and b7 bishop; the bishop is unprotected—is “loose”—making it a good target. The next question is whether the square you need (d6) is protected. It is, by Black’s bishop at e7. But then consider how the board would look if the bishop moved to d6 to take the knight. See that Black’s queen would then be taken by White’s bishop at g5; in other words, Black’s bishop is pinned to his queen. Nd6+ thus wins Black’s b7 bishop without fanfare. There is another point to consider here. You want to think not just about what your tactical moves will achieve in the way of material gains, but also about how the board will look after the sequence you want to play. This point applies to all tactical operations; we will encounter it constantly. The important point here involves the work that your e4 knight is doing before it is sent off to inflict a fork. It's guarding the bishop on g5. To be more precise, at the start of the pictured position the bishop is protected twice (by White’s two knights) and attacked twice (by Black’s bishop and the queen behind it). The bishop therefore was safe: if Black captured it, White would recapture; if Black captured again, White would recapture again. But when White sends his knight off from e4 to d6, the bishop loses one of its guards. While this doesn’t matter so long as White is keeping Black busy with checks, notice the hazard that arises once White plays NxB at the end of the

Dg010: Black to move Dg010: Black’s knight is on a dark square. So are several of White’s pieces, most usefully his king and e1 rook, which can be forked from f3. But notice as well that f3 appears to be protected by the rook on e3. So examine the rook and its freedom of movement, playing through its move and what would then be possible in your mind’s eye. If 1…Nxf3+; 2. RxN—and then Black can play RxRe1. White’s queen wouldn't then be able to recapture at e1 because Black would have a second rook still trained on the square. The point: White's rook on e3 is pinned—not to its king, but to the other rook at e1. One way or another Black gains a pawn and the exchange. (Capturing a rook in return for a bishop or knight is known generally as “winning the exchange.”)

Dg011: Here is an important twist. Black’s most advanced knight is on a dark square. So are White’s queen, king, and rook, with the latter two pieces subject to a fork at c2. But c2 appears to be protected by White’s queen.

by White’s queen. Ne6+ thus wins the queen without further ado. Dg013: With White’s knight and Black’s king and queen all on light squares, conditions seem right for a fork on f6. Is the square protected? Yes, by the Black bishop on e7. If White tries to first capture it with his own bishop, then Black recaptures with his queen and the fork is ruined. Dg011: Black to move The queen is not constrained by a pin—yet. But examine the fork by actually playing it in your mind’s eye, imagining the knight on c2 and not on b4. When you so imagine a move or exchange, pay attention to what lines are opened and closed by it and what consequences may follow—especially new pins and new possible checks. In this case, once the knight moves the White queen is pinned by Black’s queen. So play goes 1. …Nc2+; 2. Kf1, QxQ (without this intermediate step, all is lost; do you see why?); 3. NxQ, NxR. This time the lesson is that you do not just ask whether the troublesome piece currently is pinned; you ask, too, whether it would be pinned if you made the forking move.

Dg013: White to move But again the trick is to imagine the fork, mentally placing the knight on f6 and not on e4. Then you can see that once the knight moves, the Black bishop becomes pinned to Black’s queen by White’s queen—another “discovered” pin. The point repeats: don’t just ask whether moves are possible; picture moves, visualize whatever countermoves seem to make them impossible, and ask what would then be possible if the countermoves were made.

2.1.4. Exchanging Away the Guard.

Dg012: White to move Dg012: A similar problem. White’s knight is on a dark square. So are Black’s king and queen. A fork is indicated at e6. The square appears to be protected by the pawn at d7, so look more closely; imagine the knight moved, and observe that the pawn then will be pinned

Now let’s assume an enemy piece guards the square your knight needs, and it isn't pinned. Perhaps you nevertheless can get rid of it. Sometimes the guardian of the forking square may be captured: you can take it, and the piece that recaptures yours no longer will protect against the fork. Dg014: The position of Black’s king and rook make the idea for White clear enough: Nf7+. But f7 is protected by Black’s knight. Ask if it can be captured, and see that it can be―with

White’s rook. After playing RxN, White loses the rook to f6xR; but he regains it with the fork Nf7+, capturing Black’s rook next move and leaving White a knight to the good.

Dg015: Again one of White’s knights is pretty far advanced up the board on f5; any knight planted on the fourth or fifth rank is a constant forking threat. So White does a quick scan for forks and observes that the knight is on a light square along with Black’s king and queen―which can be forked with Ne7+. The needed square is protected by one piece: the bishop on d6, but White can take out the bishop with his rook now on d1. So White picks up a piece, and if Black recaptures White can follow up with the fork: 1. RxB, c7xR; 2. Ne7+.

Dg014: White to move

Remember when you play a capture that your opponent may not be required to recapture. Usually that will be his choice, but in principle he also may be able to make some other capture or counterthreat of his own. Here Black can reply to White’s RxN by playing RxN himself. Doesn't this end the forking threat? It does, but at a prohibitive price; for then White has Re8#—a classic back rank mate that takes advantage of the way Black's king is stuck in the corner. At the outset of the position the Black rook on d8 is the only piece protecting against this mating threat, so it can't afford to leave its post. We will study back rank mates in detail at various points later in this project (they get a section to themselves toward the end).

Dg016: White to move Dg016: The thought process is identical: White examines his knight’s moves, or perhaps does a color scan and notices that his knight and Black’s king and queen all are on dark squares; one way or another there is a potential fork in Nd7+. The hindrance is that the bishop at c8 protects the needed square. Can White capture the bishop? Yes, with his queen—a sacrifice worth making for the fork that follows. So White picks up a piece, and if Black recaptures White can follow up with the fork: 1. RxB, c7xR; 2. Ne7+.

Dg015: White to move Dg017: White to move

Dg017: Your most advanced knight is on a light square, as are Black’s king and queen; there is a potential fork at e7. Ask if the square is safe, and see that it is guarded by the bishop at d6. Now look for pieces you can use to attack the bishop and notice the queen at d1―but also the knight at c4. It is important to notice both. The question is not “do you have a piece attacking X?” It’s “how many of your pieces—plural—attack X?” You don't want to sacrifice your queen when a knight will do, especially as it would make the sequence a wash, Correct is 1. NxB; c7xN; 2. Ne7+.

When you capture the f7 pawn at the beginning, you should not assume that your opponent necessarily has to recapture the way you would like. He might prefer to let the pawn go rather than play into your hands; it depends on the quality of his alternatives. Here Black has the option of replying to Rxf7+ with Kg8, which loses the pawn but also takes the king out of forking range. What happens next? Imagine the board with White’s rook on f7 and Black’s king on g8, and you should see that White then has an easy capture of a piece with RxN: the rook has protection from the knight on g5, and so cannot be recaptured by Black’s king.

Dg018: White to move Dg019: White to move Dg018: The pattern repeats. White can fork three Black pieces with Ne6+. The only difficulty is the pawn at f7 that guards the needed square. There are various things one can do about such problems. The most obvious is simply to capture the pawn if you can, so here it goes 1. Rxf7, RxR, and now the pawn has been replaced by a piece that can't protect the e6 square. True, White sacrificed a rook to the cause; but now Ne6+ wins the queen. And then after Black recaptures RxN, White picks up a pawn that has been left loose by the sequence: Qxg6. White ends up trading a knight and a rook for a queen and two pawns. You might imagine that the g6 pawn could be protected by Black's king, which (on this theory) would have escaped the knight fork by moving to f6. But if Black does move his king there, White mates in three moves. It starts with Nc3-d5+. Black has no good replies; if he plays BxNd5, for example, White has Rf1+. This forces Black to play KxNe6. Now White replies e4xBd5#.

Dg019: The usual color scan reveals a potential knight fork to be had at d6, but the square is protected. How many times? Twice—by the bishop at f8 and the knight at f7; be sure to account for all the guards, not just the first you notice. Fortunately White has bishops attacking each of the two bothersome pieces, but there still is a complication: when White’s bishops take Black’s bishop and knight, Black will use his king to recapture, and the king is supposed to be one of the pieces in the fork. Will its recaptures ruin the forking opportunity? Not necessarily; so long as the king ends up on f7 it still can be forked. But this means that it is important to perform the exchange on f7 last so that the king ends its travels there. Thus 1. BxB, KxB; 2. BxN, KxB; and now Nd6 forks king and rook and so wins the latter. Naturally Black might prefer to bow out of this sequence earlier, giving up a piece rather than stepping into the fork. That's often how

tactics work, as we will see many times (but won't always point out): the victim can escape final execution of the fork or other idea, but only by making a sacrifice. In that case— which is normal—the tactic still must be counted a success.

both out of commission. And it gets better still: once Black's bishop on d5 is out of the way, White's rook on d1 attacks the Black rook on d8. So when White plays the fork, as he now can, he can use his knight to take the d8 rook without fear of recapture by the Black rook on e7.

The point to take away from this example, apart from the importance of accounting for multiple defenders, is that the order of operations in a tactical sequence can matter a great deal. Here the tactic doesn't work if White takes Black’s knight first and his bishop second. When you consider a sequence that involves more than one exchange, ask whether changes in the order of the moves would make a difference to the outcome. Dg021: Black to move

Dg020: White to move Dg020: Black’s queen is about to take yours for free. Your initial impulse might be to retreat your queen or play QxQ. Maybe one of those moves is right, but don't play either until you have asked whether they can be fit into an offensive plan. White’s most advanced knight is on a dark square; so are Black’s king and one of his rooks, suggesting a fork at f7. Before you do anything you ask whether the needed square is protected, and how many times. Again, twice—by Black's bishop and queen. Unless you can eliminate both defenders of f7, no fork. Each of the defenders is attacked once: the Black bishop by your rook at d1, and the Black queen by your queen. The natural thought is to try QxQ, which you were considering anyway for defensive purposes, and then to notice that Black’s recapture, BxQ, leaves the forking square f7 loose for your knight. Capturing one of the two guardians in the right order thus takes them

Dg021: By moving to e2 Black’s knight would fork White’s king and queen. But the needed square is under protection—twice, from White’s knight and rook. Each of the guardians is attacked only by Black’s queen. So imagine taking out one of them, and then imagine taking out the other. If QxN, then White replies f2xQ (or BxQ) and the White rook at e4 still guards the needed square. But if Black begins with QxR, then White replies NxQ and now e2 is available for Black’s knight. Once more, an exchange of one of the two guardians effectively gets rid of both of them, as guardian #2 has to recapture the piece that captured guardian #1.

2.1.5. Distracting the Guard. In the positions we just considered, the guard of the forking square always was under attack by one of your pieces, making possible an exchange that freed up the square for your knight. But what if none of your pieces are trained on the enemy pieces doing the guarding? Then capturing the guard won't work, but there are other questions we can ask. Here's a good one: is the guard also protecting some other piece or square that you might attack, thus distracting the guard away from its de-

fense of the forking square? This theme— distracting the guard—is one we will consider at many points in these materials; it gets a chapter to itself toward the end.

Dg022: White to move Dg022: In the example, the arrangement of White’s e5 knight and the Black king and queen naturally suggest a fork with Nf7. The difficulty is that f7 is guarded by Black’s rook. This time you can't capture the rook, so ask if it protects anything else you can take. It does: White plays QxN; if Black recaptures RxQ, the f7 square is left loose and available for White’s knight. The fork Nf7+ then wins back the queen with the gain of a piece. Dg023: Black has worries; he is up a piece (though White has an extra pawn), but his queen is pinned by White's rook and seems about to be lost—and his knight on f4 is hanging (in other words, it is under attack and has no protection). Look for counterplay before falling into a defensive mindset. Black’s knight and White’s king and queen are on dark squares, suggesting a possible fork at e2. Alas, e2 is protected by the knight at d4.

Dg023: Black to move

You look for ways to take out the knight directly but find none. So now look more closely for anything else the knight protects that you might take. It guards the rook at c6, which you can capture with your queen— extinguishing the pin as well. So 1…QxR; 2. NxQ, Ne2+ and the fork is made. Black wins the exchange, having traded queens and swapped his knight for a rook.

Once you see the relationship between the rook on c6 and the potential fork far away on e2 (they are connected by the knight on d4, which guards against both of them and thus is overworked), you can choose between exploiting the situation at either end. In other words, you can (a) play the sequence just described, or (b) start with Ne2+, allowing White to play NxN, and then playing QxR since the White rook’s guard (the knight) has abandoned its defensive duties. Which sequence is better? Either way you end up ahead the exchange, but the first sequence also has the advantage of getting the queens off the board—which magnifies the significance of Black’s material edge. That last idea is worth another minute of explanation if it's not already familiar. In simplest terms, the point is this: if you have one piece and your opponent has none, this lets you dominate the game in a way that an edge of five-to-four doesn't. So if you win a piece from your opponent and have five pieces against his four, your usual goal is to exchange away the rest of the pieces on the board, making captures when you can; finally you are left with the only attacker (at which point your opponent probably resigns, if not sooner). Naturally it follows that if you can start whittling down the number of pieces on the board while you're gaining your edge in the first place, you want to do so—as Black does here by starting with QxR.

Dg024: Black's knight is on a dark square. White’s king and bishop also are on dark squares, creating a potential fork at f3; but f3

is protected by the queen at d1. Can the queen be captured?

Here as in the previous problem, the exchange at the beginning both made the fork possible and improved it by turning the guardian of the forking square into a target. Notice that Black really has no choice but to take White’s queen with his king; if Black’s king merely moves out of the way, White plays QxQ—a formation known as a skewer (you attack two pieces on the same line; the more valuable gets out of the way, leaving the less valuable to be taken).

No. Is the queen protecting any other piece that can be attacked? Yes, the bishop at d4— and the bishop already is one of the pieces in the fork. So if 1…QxB, 2. QxQ, you not only have a clean fork at f3; you have a better one: Nf3+ wins the queen.

There are other little trains of thought that might have brought you to the solution here. You could have just examined any checks you are able to give and then realized that 1. QxR+, KxQ leaves Black vulnerable to a fork; or you might have seen that White can attack the Black queen via Nxf7, and wondered whether there was a way to draw Black’s king onto another dark square that also could be attacked from f7.

Dg025: White to move

Dg026: White to move

Dg025: White’s queen is under attack. The obvious impulse would be to move it to prevent RxQ, but that would be premature. First take stock of your offensive possibilities. Here you have a knight to work with; it's on a dark square, and so are Black’s king, queen, and rook—and the queen and rook can be forked by Nxf7. But the needed square is guarded by Black’s king. Ask whether the king is protecting anything else White can take, and see that it guards the Black rook. So: 1. QxR+ (extinguishing the threat with a temporary sacrifice), KxQ; 2. Nxf7+ and when the smoke clears White will have gained a rook.

Dg026: White’s knight is on a dark square, as are Black’s king, queen, and both rooks; a fork at g6 suggests itself. The square is protected—how many times? Twice: by the queen and by the pawn at h7. The pawn is pinned by White’s queen, so the problem is just the defense of g6 by Black’s queen. Consider whether it is protecting any pieces that you might take and you see that it guards the rook at f8 and bishop at e5. You can’t capture the bishop, but you can take the rook with RxR. This looks a lot like the previous problem, but with a small difference: the rook at f8 is protected twice—by the other rook at d8 as well as by the queen. If Black retakes with his other rook instead of with his queen, you

Dg024: Black to move

still won’t have a fork. But then you will have another rook at f1 that you can use to attack again. Hence: 1. RxR+, RxR; 2. RxR+, QxR; 3. Nxg6+ and the fork is complete. Think of this just as a case where two exchanges were needed to lure away the guardian rather than one.

Dg028: This is the same as the previous problem but a move earlier. It is given here as a little study in how the same train of thought looks from a defensive perspective. It would be easy for White to imagine that he can afford to play a3xB since then Black's QxR is met with QxQ. But when Black’s knight is placed this dangerously it is unwise to initiate any exchanges without making sure that no forking opportunities will be created for it— as would be here.

Dg027: Black to move Dg027: It’s Black’s turn to play, and his queen is attacked by the rook at a1 and the pawn now on b4. It would be natural but erroneous for him to begin looking for places to move the queen. Black has a well-advanced knight at d4 and so should be looking for forking chances. The knight can attack the White king in one move to f3 or c2; and at c2 it can fork king and rook. The only trouble is that the queen guards the needed square. Is the queen protecting anything that Black can attack? Yes—the rook at a1. So Black plays 1. ...QxR, which is met with 2. QxQ—now making possible 2. ...Nxc2+. Black nets a rook and a pawn. One lesson of the position is that when you are under attack, sometimes the best defense is a good offense: consider a capture rather than a retreat, and ask what the board would look like afterwards.

Dg029: White to move Dg029: White’s knight is on a light square. You see a potential fork at e7, but the square is protected by the rook at e6. Can that rook be exchanged away? No, White has nothing attacking it. So is the rook protecting anything else that can be taken? The main thing it is protecting is the other rook at c6; so if that rook could be taken, the rook at e6 would have to move over to recapture, and then the fork at e7 would work. Here as in the previous example, White has a battery of rooks aimed at the critical Black rook on c6. If only the pawn at c5 weren’t in the way. Might it be removed, or simply moved? What is it protecting? The pawn at d4, which is protected twice. So if 1. Bxd4, BxB+; then 2. Rc4xB, c5xR—and finally 3. Rc1xR, RxR. Now at last the fork can be achieved with Ne7+. Structurally this example is easy enough to understand: the rook on e6 has to be attracted away to c6 for the fork to work; but before c6 can be attacked, two preliminary exchanges are needed to clear the way. What makes it tricky is that each of those initial exchanges involves choices by both sides about which pieces to use—including pieces that you

Dg028: White to move

might barely have noticed on initial inspection of the position. For example, if you’re not mindful of all of the pieces on the board it is easy to overlook Black’s bishop on g7 and to imagine that if White plays Bxd4, Black will have to recapture with his c5 pawn. Likewise, if you’re not careful it is possible to overlook White’s second rook on the c-file, and thus fail to see that with the rook on c4 and pawn on c5 out of the way, White will have a clear shot at Black’s rook on c6. The general lesson is not to let any of the pieces on the board drift off your radar screen, and always to ask whether there is more than one way for you or your opponent to capture or recapture in a series of exchanges. This position is a good example of how to work backwards from a tactical idea to several exchanges needed to make it work. It is worth considering until the train of thought is clear.

Dg030: White to move

move Nxd5. To see its full significance we need to consider Black’s king and the constraints on its movement. White can give check with Qh8. This would be mate except that Black’s king has a flight square in e7. The e7 square itself thus is a vulnerability, or target, in Black’s position; and now return to White’s Nxd5 and see that it forks the e7 square and Black’s queen. So Black has to reply BxN to avoid mate, which in turn allows White’s next fork: Nd7+. Indeed, White can turn these insights around and play an even stronger sequence by starting with Nd7+. If Black then plays BxN, White replies Nxd5 and Black has headaches: he is required to take emergency steps to prevent White from mating on h8, and finds that he has no way to capture White’s troublesome knight. He has to play g7-g6 so that his own queen has an open line to guard h8 if White’s queen lands there. But now White has NxQ, and (assuming Black moves his king to e7) NxR. Black is better off replying to the initial Nd7+ by moving his king to e7 and letting his queen be traded away for a knight. All this suits White, who still ends up winning Black's queen but at lower cost than in our original plan. How would you see these richer ideas in the position? It all starts by focusing on the enemy king, how you threaten it, and how your threats are being staved off. We will see many times how this approach to analysis pays off with useful tactical ideas.

Dg030: The usual scan of knight moves reveals that White’s most advanced knight has a fork at d7, but d7 is guarded by the Black bishop at e6. The bishop can’t be captured; you have no piece trained on it. But the bishop also guards the pawn at d5—which can be taken by your other knight at c3. So Nxd5, and you gain a pawn. If Black recaptures with BxN, you have Nd7+; after you next play NxQ and Black recaptures, you've won a queen and a pawn for two knights. That's a simple analysis of the position along the lines we have been discussing. But there also is another, better way to size it up. Let’s look a little more deeply at White’s initial

Dg031: White to move Dg031: White has several pieces bearing down on the Black king’s general position—a

queen trained on h7, a rook on the sixth rank, another rook on the f-file, and a knight nearby as well. Focus on that last piece: when you have a knight near the enemy king, the search for forks should be automatic; all those other pieces nearby are important in part because they can be used as tools to help make a fork work. In this case you see that White’s knight has a forking square in f6. The trouble is that the needed square is protected by the pawn on g7. White has no way to take the pawn, and it doesn’t protect any pieces White can take, either. But it does protect sensitive squares near Black’s king, so putting an attacker on one of those squares may be as good as taking a piece the pawn protects. Here White sees that since his queen already attacks h7, adding another attacker against that square would create a mate threat. (This is a common formula: if your queen attacks a square adjacent to the enemy king, adding another attacker against the same square often creates a threat of mate.) Thus White plays Rh6. The rook now provides the cover White needs to play Qxh7# next move. To prevent this Black has to play g7xR—and now the f6 square is available for White’s knight. He plays Nf6+, and after NxQ next move White has won a queen for a rook. We see again the power of combining our knowledge of the knight fork with a close look at your mating threats against the enemy king.

Dg032: White to move Dg032: Here is another application of the same idea: thinking about whether you can distract a guard by making a threat from a square it protects. Here White’s knight is on a

dark square. So are Black’s king and queen, and they can be forked at e6. The trouble is that the square is protected by the Black bishop on f7. The bishop can't be captured; none of White’s pieces attacks it. Nor is the bishop quite protecting any pieces that White can take. It guards the d5 pawn, but so does the c6 pawn. But now you also can ask whether the restricted bishop is protecting any squares that White can occupy. Mostly you want to see if it is guarding any squares next to Black’s king, because then you may be able to draw it away by threatening mate on one of those squares. Think of it this way: the bishop on f7 is confined (if it wants to prevent the fork Ne6) to the diagonal running from a2-g8; it really cannot afford to go off on the e8-h5 diagonal—so look for play there. What you find is that if White’s rook moves forward a square to h5, it checks the Black king. The king wouldn’t be able to capture it because the square also is attacked by a knight, so Black would have to respond to the check in some other way. Let's consider the possibilities: One option would be for him to take the rook with his bishop, which would clear the way for the fork White seeks. The idea is 1. Rh5+, BxR; 2. Ne6+, Kf6; 3. NxQ. This looks strong, and it is—but take a moment to ask how Black will reply at the end. He has Rc8, attacking the knight; and this turns out to be surprisingly troublesome, since the knight has nowhere safe to go. Na6 is met with Ra8, renewing the attack and the knight still has no retreat. But the knight can take a pawn on the way down by replying to Rc8 with Nxd5; and then after Black recaptures (c6xNd5), White grabs yet another Black pawn, and creates a passed pawn of his own, with Bxb5. So in the end White ends up winning a queen and two pawns for a knight and a rook. Another possibility is that Black could reply to Rh5 by moving his king to f6. So look for your next check and find Rxf5. When the king moves again in response, you ask whether any Black pieces will have been loosened―i.e., left unprotected―by all this activity, and you find KxN for White.

This problem is a good example of a valuable general point: effective combinations often require both (a) pattern recognition, and (b) skill at identifying forcing moves—especially checks—and their consequences. The key move here—Rh5+—might have been spotted in an effort to make the fork work, or it might as well have been spotted just by examining the consequences of any checks you can give and any vulnerabilities of the enemy king. You notice that one of the possible Black responses to this particular check would be BxR; you imagine the board with your rook and his bishop moved, and a simple color scan or inspection of knight moves reveals the fork waiting at e6. If Black instead responds to the check with Kf6, you look for the next check, and so forth.

Dg033: Black to move Dg033: Here is another more complicated sequence; it will take a bit of patience to untangle. Black’s knight is on a dark square in White’s territory; also on dark squares are all of White’s most valuable pieces—king, queen, and both rooks. Start by just looking at each of the knight’s moves in search of potential forks. There are two: Ne2+, forking White’s king, queen, and rook; and Nd3, attacking both rooks. Now carefully identify what prevents either of those two moves. Ne2+ is stopped by one thing: the rook at e1 that protects the square. Nd3 is stopped by two things: The knight at f2 and queen at g3 that both protect the square. Take stock next of what resources Black can bring to bear against those guardians. White’s queen can be taken by Black’s queen. As for the knight at f2 and the rook at e1, neither of them can be captured by Black. So next consider whether

they are guarding anything Black can attack, and they are: they both protect the knight at e4. Can Black attack that knight? Yes, twice: with the bishop at f5 and the queen behind it. Now begin thinking about possible move orders and their consequences, always bearing in mind that you are hoping to free up either d3 or e2 for your knight. Try BxN. How will White respond? There are two possibilities if he chooses to recapture: NxB or RxB. If NxB, then one of the two guardians of d3 has been eliminated; only the queen remains, and it can then be taken with QxQ. After White then plays h2xQ, Black can play Nd3, forking the rooks. If White instead plays RxB, the rook still guards e2. But Black can attack it again; remember that when two pieces are lined up like the queen and bishop here, they attack e4 twice. So Black plays QxR, and after White replies with NxQ the e2 square is available for Ne2+, forking White’s king and queen. The conclusion: Black wins by starting with BxN, because any recapture White makes in response leads to a knight fork for Black. This position is tricky because Black has two offensive options and White has choices to make as well in response to BxN. But a methodical examination of Black’s goals, the impediments to them, and White’s possible replies to Black’s captures nevertheless breaks it all down easily enough.

Dg034: White to move Dg034: Black’s knight on d4 is creating a great deal of trouble; it's about to take White’s queen and also threatens a fork at e2. The natural idea is to take the knight—but with your bishop or with your own knight? Con-

sider what else you can do with either of them. White’s knight is on a light square, and so are Black’s queen and rook (and his king, but for now only the queen and rook are within range of White’s knight). White would like to play the fork Nxe5, but now he can’t. The problem isn’t the pawn on e5; it’s the pawn on f6 that guards e5. White has no other pieces he can use to capture either pawn, but the more natural way to get rid of troublesome pawns is to capture things they protect, for then they move to recapture and no longer guard the squares they once did. So White breaks the logjam with BxN, forcing Black to recapture with e5xB. Now the path is clear for White to play e4-e5, still in an effort to get the f6 pawn to move. Black has to play f6xe5 (if he instead moves his knight away from d6, White pushes the pawn to e6 and forks the rook and queen with cover from his own queen at b3). At last nothing guards e5, so White can play Nxe5, forking queen and rook and winning the exchange. Observe how the whole sequence was driven by an idea: if the f6 pawn could be lured off of guard duty of e5, the fork would be possible; so White works on ways to attract it away with captures and threats.

protect something else, creating a way to break the jam? If White somehow could force a Black piece onto d4, then he could take it with his bishop, initiating the sequence described a moment ago. So he experiments with threats; a2-a4 forces the knight to move, and to where? A knight has a maximum of eight places it can move when attacked, and when it’s near the side of the board the number is smaller. Here there are just six squares it can reach, and only one that is available and doesn’t result in immediate capture: Black plays Nd4. And now the stage is set for the sequence examined in the previous problem. None of this is easy to see. And if you did see it, it might have been as a result not of spotting the forking idea but just of playing with threats and their consequences. You start thinking about a2-a4, see where the knight goes, imagine taking it once it lands on d4, see that this clears the way for a pawn push to e5, observe that Black needs to take the pawn, and then at last come up with the knight fork on e5 at the end. But it's a lot easier to think usefully about these things if you know that you have a potential knight fork lurking on e5 if conditions change. That threat lends structure to the train of thought about your forcing moves and where they lead. Anyway, look at this position also as another study in the art of getting a bothersome pawn out of your way. If you can force an enemy piece to become a protectorate of the pawn, you can then capture the piece and force the pawn to recapture, moving out of the way.

2.1.6. Getting Out of Your Own Way. Dg035: White to move Dg035: Here is the same position still one move earlier. The train of thought starts the same, but here there is no way to get the e5 pawn off of its square by attacking something it protects; for it protects nothing. Observe the difficulty of forcing an enemy pawn to move when it protects nothing that you can capture. Don’t give up, though: can you play a forcing move that will cause one of the pawns to then

You don't want to overlook a potential fork just because the forking square already is occupied by one of your own pieces. Ask: can the piece that is in the way evacuate the square violently, thus requiring a timeconsuming response from your opponent and making the fork possible on your next move?

Dg036: In this first example White’s knight is on a light square and so are Black’s king and rook.

smashing finale if your opponent recaptures after each of them; but of course he may not recapture, leaving you with lesser gains. In a good game of chess this often is the importance of seeing tactics. You may or may not actually get to play the fork, but seeing the threat of it allows you to make other gains.

Dg036: White to move Or just look at the knight’s potential moves without being distracted by pieces of your own that already occupy the squares the knight might like to reach. Either way the point to notice is the potential fork at f6. The trouble is that White’s own rook already is on the square. There is standard method for dealing with this: Ask whether the rook can be moved in a way that requires an immediate reply from Black, keeping his king and rook where they are. A capture is good for the purpose, and the one possible here is RxN: it calls for Black to respond b7xR, and White then follows up with Nf6+. Keep track of what you are losing and gaining. Here you have sacrificed a rook for a knight, and are about to win a rook. But then won't you lose your knight after the fork, leaving the sequence a wash? No, though that would be true if Black could respond to the fork with Kf8, for then after NxR Black could play KxN. But here Black can’t play Kf8 because White has a pawn guarding the square. Black has to play Kh8, and then White wins the rook cleanly. When we say that White's initial RxN "requires" or "calls for" Black to play b7xR, this should not be taken literally. If Black sees this sequence coming he will respond to RxN by forgetting about his lost knight and instead moving his king to avoid the fork at f6. This is a point common to many of our studies: you have a series of captures that lead to a

Dg037: White to move Dg037: White’s knight is on a dark square; so are Black’s queen and rook. Thus there is a forking square at f3 which is easy to overlook but should be made no less visible to you by the presence on it of White’s own queen. You need a move for the queen that forces a response from Black, making Nf3 possible. You might first see QxN, but look harder for a check or capture that doesn’t require you to sacrifice the queen. Correct is 1. Qa8+. 1. … Kh7 then is forced (Ne8 just loses the knight); and 2. Nf3 can then follow. White wins the exchange. Most of our forks so far have involved the enemy king as one of the targets, but not this one. When the enemy king is not a party to a fork you are considering, it is important to pause and ask whether either of the forked pieces would be able to break out of it and do damage or seize the initiative with a check. In this case that’s not a problem, though; neither Black’s queen nor his rook has a good option. Dg038: A color scan or a look at the White knight's circle of moves turns up a potential fork to be had at e6, and again its potential should not be obscured by the presence of White’s queen there. The question is whether the queen can make a move that will force

Black’s response, giving him no time to prevent the fork Ne6+ a move later.

Dg038: White to move First you look for a check, but it turns out that most of the squares from which the queen can attack the king―e7, e8, f6, f7, g8, d6—result either in (a) the queen being captured by Black’s king or queen, which ruins the fork, or (b) the king simply moving, which likewise ruins the fork. But if you persist you come up with 1. QxR+. If 1. …RxQ, then 2. Ne6+, forking king and queen; and if not RxQ, so much the better: after 1. ...Ke7, White can play QxRc7+ and has still more fun from there.

check. There is just one: QxN. What follows from that? Either g6xQ or RxQ; and either way, Ne6+ picks up Black’s queen and wins a knight with the sequence. Incidentally, it may come as a small surprise to you to hear that White's rook on c1 is doing absolutely essential work in this position. Do you see why? It protects f1. If the rook on c1 were gone and f1 thus were unprotected, Black would reply to QxN with RxQ, aiming his rook at White’s back rank—and then after White finishes his knight fork with NxQ, Black has Rf1#, checkmating White’s trapped king. The moral: be ever mindful of your own king’s vulnerabilities and how any offensive sequences you are planning may unexpectedly expose it to checks (and worse) that are not possible on the board in front of you.

Dg040: White to move

Dg039: White to move Dg039: White’s knight is on a dark square. So are Black’s king, queen, and rook. Ne6+ would be great, but White’s queen is in the way. The question, now familiar, is whether the queen can make a move that will force a response from Black that costs him a move. You might start by examining, if briefly, any checks the queen can administer, but all of them cause either Black’s king or queen to move, ruining the fork. So now look for captures the queen can make without giving

Dg040: This example combines two recent points we have studied. The initial key is to see the potential knight fork Nd5 despite the fact that you already occupy d5 with another piece. The question is how best to vacate the bishop from the forking square. It runs on the light squares and the king is on a dark one, so the bishop won’t be able to deliver a check. Is there anything that it might capture? Yes: Black’s bishop. But before you play BxB, notice (as would be obvious in a game) that Black is about to play QxQ, ruining your fun. So the correct play goes 1. QxQ, RxQ; then 2. BxB, b5xB; 3. Nd5, forking the rooks. This position, like the previous one, contains a rook that looks unassuming but that provides crucial support for the whole sequence: the one on f1. Imagine it gone and rethink the

position. Now in reply to 3. Nd5, Black moves his rook from e7 to d7; and if White then plays the capture NxRf6, Black has RxRd1+. (In effect Black uses his rook to pin the White knight to the White rook on d1.) In the actual position White’s rook on f1 prevents this because it protects the rook on d1. The general lesson you can draw from this little note is that loose pieces (as the d1 rook would be if the f1 rook were gone) are a hazard. Even if they don’t appear to be part of the action, they can find themselves suddenly captured during or after a sequence you are planning elsewhere.

2.1.7. Unsuitable Targets. Sometimes a knight fork is available but only one of the forkable pieces is a good target; the other is a piece of equal or lesser value to your knight, and perhaps is guarded. The question then is whether the bad target can be made a good one through an exchange.

Dg042: White to move Dg042: White’s knight is on a dark square. Black’s queen and knight are on dark squares (and also the king, but at the moment it’s too far away to fork). So you need to see that White has a potential fork at e4 but that one of the targets is Black’s knight, which won't do. Ask whether White can take the knight with something else and thus cause it to be exchanged for a suitable target. He can, by playing QxN+; if Black responds KxQ, White has Ne4+, forking king and queen. He ends up gaining a knight. Throwing away your queen to take an enemy knight looks counterintuitive, but a temporary sacrifice of this kind is a common opening thrust in a tactical sequence.

Dg041: Black to move Dg041: We start here with a case where at first glance there might seem to be no forking possibility for Black. The point to see is that Nc5 is a potential knight fork even though it won't work now because one of its targets is another knight (so Black's Nc5+ is simply met with NxN). Ask whether you can make your opponent replace the knight with something better by forcing an exchange. Here Black gets it done by taking the knight with his rook: 1. …RxN, BxR, and now Nc5+ wins the bishop and thus gains two pieces for the rook.

Dg044: White to move Dg044: White’s knight is on a light square; Black’s king and knight also are on light squares and can be forked at e7. If you notice the forking idea at all here—in other words, if you aren't lulled into overlooking it because the target on c6 is another knight—you are most of the way home. Of course the knight is an unsuitable target, so you force Black to

replace it by first taking it with another piece. Thus 1. QxN; QxQ; 2. NxB+. After playing out the fork White has won two pieces.

knight can be taken by any of White’s pieces, and see that one of them—the rook—is ready to do the job, and with check. After RxN+ Black appears to have a choice of recapturing with his queen or king, but on closer inspection the queen is pinned. So the only recapture is KxR; and then Nc5+ follows. And again the same result can be reached by just experimenting from the outset with the check RxN+. After the recapture KxR you see Black's king and queen in the telltale position for a knight fork.

Dg045: Black to move Dg045: Nxd4 looks implausible for Black because it loses a knight for a pawn. But the implications of the move change when you see that it is a fork, attacking the knight on e2 and the queen at f5. For then you see the real question is whether White's knight can be replaced with a working target. It can: Black plays 1. … QxN+; 2. KxQ, Nxd4+, winning back the queen with the net gain of a pawn after White recaptures RxN. Like many of these positions, this one can be solved as well by having a look at the consequences of any checks you can give. Black’s queen can deliver check in four ways; one of them, QxN, moves the king into a new position in which the fork might be seen if it wasn’t already.

Dg046: White to move Dg046: White’s knight is on a light square, as are Black’s queen and knight. The structure of a fork is there; if the Black knight could be replaced with the king, the fork would become playable with Nc5. So ask whether the

Dg047: White to move Dg047: White’s knight is on a dark square, along with Black’s knight and king. There is a potential fork at f5, but the g3 knight is pinned, f5 is protected by both queen and knight, and anyway the fork is of no use because it ends up trading a knight for a knight. So it’s only the barest glimmer of an idea, but when you ask whether you can capture the d4 knight with something else (and what happens then) you find 1. QxN+, QxQ; 2. Nf5+, a knight fork that wins a piece. Regardless of whether the fork occurred to you at the start, consideration of QxN+ would have been mandatory because it was one of White’s three possible checks. We keep emphasizing these separate paths to the solution—i.e., showing how it might have been found by looking at checks and their consequences—because in many positions the idea isn't as clear at the outset as it perhaps has been in these early positions; and in that case starting with a look at your forcing moves is the best way to find tactical ideas. In this case, after imagining QxN+ and the recapture QxQ

you reevaluate your knight's tactical prospects. You notice that your knight and Black’s queen and king all would be sitting on dark squares (and the knight would have become unpinned), calling for the fork Nf5+.

Dg048: White to move White’s knight is on a dark square; so are Black’s bishop and rook. You see a knight fork at c6. But it won’t work because Black can respond by moving his rook to e8, both taking it out of harm’s way and using it to protect the bishop. As we know, this is a common difficulty when forking two pieces neither of which are the king; one often can move to protect the other. Can you improve the target by capturing one of the pieces and forcing an exchange? Yes, with RxB+, to which Black replies KxR. Then comes Nc6+, and now White wins the rook; moving the rook to protect the other piece doesn’t work anymore for Black because now the other piece is a king.

Dg049: White to move

Dg049: White’s knight is on a dark square. Both of Black’s rooks and his bishop likewise are on dark squares and are positioned for a fork at d7. Black’s queen guards the square but can be eliminated with the simple capture 1. QxQ. Consider Black’s possible replies to that move. RxQ is out because the rook is pinned. It will have to be 1. …KxQ or 1 …BxQ, either of which leaves d7 available for White’s knight. Yet this is no good because then Nd7 is met by Black with RxR! Again, when you are forking pieces and none of them are a king, you need to ask what damage any of them might be able to do while breaking out of the fork. And anyway you should not be settling for a fork of a bishop and rook when the king is so close to being on a forking square as well. So after the exchange of queens White plays 2. RxR+, KxR―then Nd7+, winning a rook with the sequence.

Dg050: White to move Dg050: Now combine the current theme with an earlier one. A routine color scan (or a look at your checks, or a look at your knight moves) turns up a potential fork of Black’s king (good) and knight (no good) to be had by playing Nxc6. Can the knight on b4 be exchanged for something better? And what about the fact that the forking square, c6, is guarded? Experiment with exchanges that may clarify the board. 1. Ra4xN leads to 1. …RxR; now the fork has a better target in the rook, but the forking square still is protected by the second Black rook at b6. So it becomes a straightforward problem of attracting away

the guardian of the forking square by attacking a piece it protects. Just do another exchange: 2. RxR, RxR then allows Nxc6+.

keeps the opponent too busy to do anything about the forthcoming fork. In this case the initial move Nf8 threatens Black's queen, so his choice of replies is very limited. 2.1.8. Playing Defective Knight Forks.

Dg051: White to move Dg051: This one takes a little imagination. You might start by seeing the capture you have available: QxN. It doesn’t work because Black’s knight is guarded by its queen. Might you be able to chase away the queen, as with Nc5 or Nf8? No, because the queen just moves to another square from which it guards the knight (e.g., Qe8 or Qd6). But when your own knight is nearby the thought of a fork always is there, and now such a possibility comes into view: notice the position of Black’s king and knight; they are on squares that are poised to be forked. If Black’s queen were substituted for his knight, White’s knight could fork them if it could get to g6. White’s knight can’t get to g6 from its current perch, but in two steps it becomes possible. First comes Nf8, attacking Black's queen. The queen moves anyplace where it still can protect the knight; White plays the exchange 2. QxN, QxQ; and now 3. Nxg6+ imposes the fork, wins back the queen, and gains White a piece. Another way to think here, I suppose―the reader can judge its utility―is to say it's a case where the knight isn't on the right colored square at the start, so it needs to make two moves rather than one: first a move to a dark colored square, to match the one where the king sits; then, after the queen is likewise moved to a dark square, the fork from g6. But notice that this pattern―two knight moves―is likely to work only when the knight makes a threat on its first move which

Suppose you spot a potential fork but find that the forking square is defended and there is no way to pin the defender, capture it, or capture anything it protects. It still isn’t time to give up; instead, imagine going ahead with the fork and letting your knight be captured. Picture the board as it then will look: without your knight, and with your opponent’s guard moved from its current square onto the forking square. What then would be possible? Consider the consequences of any checks you then would be able to inflict; consider whether the stage has been set for another fork; consider whether any pieces that used to be protected now are loose; consider whether any open lines have been created that would allow you to pin one piece to another. Indeed, sometimes playing fork and letting it fail is more powerful than "perfecting" it by removing the guard of the forking square. And sometimes you thus will find that an implausible-looking fork works after all because the cost to your opponent of taking your knight is too high. All this will be made clear with some examples. In the position to the left White has the makings of a fork with Ne7+, but e7 is protected by the Black queen. The queen cannot be captured or threatened, and White can’t attack anything else the queen protects. So: what if White goes ahead with the fork and Black plays QxN? Dg052: What will the board then look like? Two things will have changed: the White knight will be off the board and the Black queen will have moved from e6 to e7. Both changes are significant. The removal of the knight creates an open line on the c-file, allowing the White queen to attack the rook at c8; and the movement of the Black queen removes the rook’s protection, leaving it loose.

You might as easily have seen the idea the other way around: you observe that your battery of rooks on the g-file nearly is ready to mate on g8, but that the bishop on g7 stands in your way; this means the bishop is pinned (we will see many studies like this in the chapters on pins), and is not really defending e5. Since the e5 pawn’s other defender also is pinned (to its queen), e5 is available to your knight for a possible fork. Dg052: White to move So White then plays QxR+ and takes a rook for a knight, winning the exchange.

In any event, if Black sees all this as well as you do (and you should assume he will), the actual consequences of the forking move Nxe5 still require some thought. If he tries to forfeit “only” the exchange by just moving his queen and letting go of the rook on f7, Black ends up losing more than that; for White can instead take the rook on c4 at no cost. Notice that once White plays Nxe5, the c4 rook is attacked twice by White and protected only once by Black. So the lesser evil for Black in reply to 1. Nxe5 probably is 1. … d6xN; 2. RxQ, RxRc6 losing his queen and a pawn in return for a knight and a rook.

Dg053: White to move Dg053: Both White knights are on light squares. So are Black’s queen and both of his rooks. The knight on d5 has no forking moves, but the knight on d3 has one: Nxe5, forking the queen and both rooks. Is the square protected? Yes―twice (all defenders must be accounted for!). Start by worrying about the pawn on d6. It turns out to be a nonissue because it is pinned to its queen by White’s rook at g6. That leaves the bishop on g7 to consider. Imagine the board after 1. Nxe5, BxN. What lines would that exchange open, and what checks would you then have? Just one: Rg8. Examine its consequences and you find that they can be summarized in a word: mate! For when you imagine the king fleeing to e7, notice that your d5 knight already attacks the square; and you should be mindful from the beginning of the battery of rooks you have bearing down on the g-file adjacent to the king.

Dg054: White to move Dg054: White’s knight is on the same color square as Black’s king and queen and can fork them at f7. Black protects the square with his rook. If White tries to start by taking out the rook with his queen, Black recaptures with his own queen and the fork is spoiled. If White plays QxQ, however, Black replies with RxQ, and now the fork works, winning White a rook. Yet with king and queen positioned like this it would be rash to settle for a rook; consider what happens if White simply goes ahead with 1. Nxf7+ and allows his knight to be captured by RxN. Now Black's

queen is left loose for the taking with QxQ, which mates a move later (after Black gives a futile interposition with his rook). So the fork 1. Nxf7+ works after all, as the lesser evil for Black is letting his queen be taken by White’s knight—after which Black recaptures with his rook, allowing White to then play QxR+. White ends up with a queen and a rook against Black’s two knights, an easy win from here. Dg056: White to move

Dg055: White to move Dg055: 1. Ng6+ looks like a promising fork of Black's king and rook, impeded only by the knight at e7. One way to handle this, of course, is to capture the knight with 1. RxN, to which Black replies 1. …BxR. Now the fork Ng6+ wins back the exchange, but the sequence is a wash. So start again, taking a moment to look at what happens if you try for the fork without clearing g6 and just let the knight get taken. Notice especially the battery of two rooks on the seventh rank, which is always a powerful combination. If Black replies to Ng6 with NxN, that opens the seventh rank; what checks does White then have? Answer: just one; RxR―which is mate. So Black doesn’t dare play 1. ...NxN; in effect his knight is pinned to the mating square at h7. White’s best bet thus is to play 1. Ng6+ straightaway followed by NxN, as this wins a whole knight for free—a rare case where a knight fork wins a knight. If White instead finishes with NxR, he merely wins the exchange, as Black will then be in a position to recapture with his king (it would have moved to g7) whereas if White finishes with NxN Black can't recapture with his rook because his king is in the way.

Dg056: White’s knight and Black’s queen and rook are on dark squares; White would like to play Nh7 to fork them, but then Black’s king can capture the knight. So what then? Consider the position that results. When the king or the pieces around it move, it’s always wise to begin by checking for any pieces that may have become pinned—pieces, in other words, that now find themselves lined up with the king and that can’t move without exposing it to attack. Here the king’s move to h7 would cause the pawn on g6 to become pinned. As we know from earlier studies, a key consequence of a pin is that the pinned piece can't guard anything because it can't move. In this case the pin of the g6 pawn means the h5 pawn—and perhaps more importantly the h5 square—are left loose. Perhaps you can take advantage. Carefully examine any check that could be given from there. Think of Qxh5+. The king would have to retreat to g7 or g8. With the rook behind it, the queen then can move in for the kill: Qh7#. So the original knight fork Nh7 does work, winning the exchange; Black can't afford to play KxN, and so must move his queen and let his rook be taken. But it only becomes possible to see this once you imagine what would happen if the fork "failed" because your knight got taken. Dg057: White’s more advanced knight has no potential forks except the ineffective Ne6. The less advanced knight at e4, however, is on the same color square as Black’s king and queen, suggesting a fork at f6. The needed square is protected by Black’s bishop at g7, and on inspection you see that the bishop

cannot be pinned, captured, or lured away by an attack on one of its protectorates.

Dg057: White to move But imagine proceeding with the fork anyway and allowing BxN; in other words, picture the board with the knight on e4 gone and the Black bishop moved to f6. You are especially interested in whether that sacrifice might make an attack on Black’s king possible, so study its position carefully. Consider any pins that would be in place and any lines that would have been opened by that little exchange. Starting with pins, White’s bishop at c4 already pins Black’s pawn at f7, and still will do so after 1. Nf6+, BxN. As for open lines, the move of the e4 knight would have opened a path for your queen to g6, where it would be possible for you to give a new check (g6 is loose; this is the significance of the pin we just noted). In reply to 2. Qxg6+, Black would be able to play Bg7 or move his king to h8; either way mate follows with Qh7, since h7 is guarded by White’s remaining knight. So the original fork at f6 wins at least the queen for a knight, and delivers mate if Black is careless.

Dg058: White to move

Dg058: White’s knight is on a light square, along with Black’s king and queen. Examine every square the knight can move to and a fork at d8 suggests itself; but d8 is protected by one of Black’s rooks. You look for ways to pin, capture, or distract the rook, and find none. But before giving up on the thought, imagine carrying out the fork and letting the knight get taken; ask how the board would look with the knight gone and the rook moved to d8. Methodically imagine any checks you then would have. The most interesting is Qxe7, since it's safe and attacks not only Black's king but also the now-loose rook on d8. How would Black respond to the latter threat? With Kg8; it would be his only legal move. Now White has the simple QxR+. Here the fork is just a means to an end, viz., capturing the rook and winning the exchange.

Dg059: White to move Dg059: White’s knight is on a light square, as are Black’s king, queen, and rook. You try first to fork the two more valuable pieces and so see that Nxf6+ attacks the king and queen. The trouble is that g7xN follows. Black’s gpawn can’t be pinned, captured, or distracted. But you must habitually persevere, playing the moves in your mind’s eye and imagining the aftermath and its opportunities: think of the board without White’s knight and (in effect) without Black’s g-pawn, which will have replaced his current f-pawn. Examine every check you then would have—with every piece. There would be three: Qf5; Qxd4; and Rxd4. The first, Qf5, is met with QxQ and nothing more. The second, Qxd4, causes Black to play QxQ and then White to play RxQ+; the king moves, and in the end White has traded his knight for two pawns. But

Rxd4+ is another matter. If Black moves his king, White plays RxQ. If Black plays QxR, White plays QxQ. So the original move, Nxf6, is a good one, gaining Black’s queen and two pawns in return for a knight and a rook.

Dg061: Black to move

Dg060: White to move Dg060: White’s more advanced knight at f5 has no good forks; the only Black pieces on the knight's square color are the king and bishop, which can’t be reached from any square within range. White’s other knight, though, is on a dark square (d4), and so are Black’s queen and one of his rooks. So how about Nxc6? The square is protected by Black’s bishop, which can’t be pinned, captured, or distracted. But still: if White plays Nxc6 and Black replies with BxN, what then is possible? Imagine White’s d4 knight off the board and Black’s bishop at c6, and then examine every check. There are two: Nxh6+, which doesn't help, and Ne7+—which forks the king and bishop. Then it gets even better: Black has no alternative but to move his king; White then plays Nxc6, winning the bishop and inflicting yet another fork, this time of Black’s queen and rook. Now it's safe because the bishop is gone. A lesson of the position: anytime a sequence calls for a knight to move in enemy territory, think about whether its move might be a (or another) fork. Remember that every move by a knight changes the color of the square on which it sits, and thus may radically change its forking prospects.

Dg061: Black’s advanced knight at c3 is on a dark square. So are White’s king, queen, bishop, and rook; examine the knight’s ring of possible moves, and see that the king and queen can be forked at e4—but that the square is protected by the pawn at f3. Can the pawn be pinned, captured, or distracted? No, no, and no. Okay; what results if Black plays the fork anyway and permits f3xN? Visualize what is left on the board. Black then has two checks—Qd2 and Qe1—but neither are helpful since White captures the queen in either case. Nor does Black have any further knight forks. But remember that when considering an exchange you also want to examine what lines would be opened by it and what pins then would exist or become possible. Here, moving White’s f-pawn to e4 would put White's king and queen on the same file with nothing between them. Anytime you see this pattern you should be thinking “pin”; the opponent’s second piece will be powerless to move when attacked if moving would expose the king. (Consider this a preview of the patterns we will be studying in our later work on pins.) Here Black would be able to pin the queen with Rf8 and take it a move later. So the original Ne4+ ends up winning the queen after all in exchange for the knight and a rook. If you didn’t spot this, it’s probably because you haven’t studied the art of the pin in any detail—a problem we will cure later. But the next couple of positions also will offer some practice in thinking about pins that may arise after a "failed" fork. Watch for them. Dg062: White’s knight is on a light square, as are Black’s king and queen, calling for con-

sideration of a fork at b6. Black guards the square with the pawn at c7, which (a brief examination reveals) cannot be pinned, captured, or effectively distracted. White nevertheless imagines playing the fork and losing the knight. With the knight off the board and Black’s c-pawn moved to b6, is anything interesting possible?

Dg063: White to move

Dg062: White to move White has one check―Qe8―but it just loses the queen. He has no more knights he can use to fork anything. But here as in the previous example he sees that Black’s king and queen are on the same line—this time a diagonal. He thinks “pin,” again, and can impose one with Be6, winning the queen. (Black replies Ne5, which will allow him to retake White's bishop after BxQ; then White has Qxg6.) Here the key thing to visualize was White’s own knight cleared from the board. The alignment of Black’s king and queen already was present; the fork serves just as a way for White to move his knight out of the path of his bishop, and in a manner that forces Black’s response before he can take measures to avoid the pin that follows. One of our general points repeats: in addition to examining every check you would have after an exchange, look for any newly open lines that might allow for a pin or other tactic.

Dg063: This position is still more demanding. A scan of the pieces on dark squares turns up a knight fork: Nxc6, attacking Black’s queen and his bishop; the latter piece makes a suitable target because it is unprotected.

But one must always ask what the response to the fork might be, especially when neither of the forked pieces is a king. Here Black has a clear saving move: Qc7, both taking the queen out of danger and enabling it to protect the previously unguarded bishop. As usual, however, this is no reason to give up on the idea. Once Black makes his reply, a new color scan or other examination of knight moves would be in order: now White’s knight would be on a light square and so would Black’s king and rook. So how about Ne7+? Alas, the square is protected by Black’s queen, now (in our imaginings) sitting on c7. And yet this still is no reason to give up on the idea, since we always can ask what becomes possible if Black then captures the knight. What lines then would be opened? What pins would come into existence? With White’s knight off the board and the Black queen ending up back at e7, White’s e1 rook would pin Black’s e6 pawn to his queen. A pinned pawn can guard nothing, and in this case the pin leaves Black’s rook at f5 unprotected. White takes it with his queen. This sounds complicated, and at first it isn’t easy to see. But you might be aided by observing a visual pattern trying to emerge. If White’s knight could vacate his square, White’s rook would pin the pawn that protects Black’s rook, which could then be taken. The forcing way for White to vacate his knight from e5 is with a fork at c6. Unfortunately Black’s queen then moves, ruining the pin White is trying to achieve; fortunately, White can draw the queen back into place at e7 with another knight move to that square. So solving this problem might involve two trains of

thought: one that sees a goal and tries to reason toward it (here, creating the pin so the rook can be taken), and one that involves looking at various attacks you can make and what their consequences would be.

within fresh striking range of a knight or other piece. Let's turn to examples.

2.1.9. Checking the King into Position. In all the positions so far a knight has been one move away from striking at two pieces. We now turn to cases where that is not yet so. Whereas the previous positions typically relied on pattern recognition—you see the structural pattern for a fork in place and look for ways to perfect it—the positions here involve the other side of tactical play as well: examining forcing moves to see where they lead. Most often we will begin the train of thought by examining checks and their consequences. Checks are the most forcing of all moves because the choice of replies to them is so limited: your opponent has to reply by capturing the piece threatening his king, or by moving his king, or by interposing something between his king and your threatening piece. And often one or two of those options will be unavailable, reducing more the number of replies you need to worry about. Pushing your opponent’s king around with checks is a good way to generate tactical opportunities. Eventually the king may end up in position to be forked (or be used to create a pin, or a skewer, or a discovery—as we shall see later). We already know that kings are ideal targets for double attacks, because when your opponent is in check he rarely will be able to use his next move to launch a counterattack. This point makes it easier to find forking ideas in the first place; for even if there is no fork yet in sight, you always can ask whether your knight is positioned to attack your opponent’s king. If it is, then one of your background goals as you play with your forcing moves is to move another of your opponent’s pieces onto a square of the same color as his king’s, and into a position where you can administer a fork. Likewise, anytime you deliver a check that forces the king to move, consider whether the king has been brought

Dg064: White to move Dg064: In the position White has no forks, so start by examining every available check. Ask piece by piece whether you have any way to attack the king and what would happen if you did—what move would be made in response and what the board would look like afterwards. Here White has just one: Ra8. It requires Black to move his king to g7. Now imagine the resulting position and ask what could be done with it—by use of a color scan or by looking for your next check. Either way, see that 2. Ne8+ forks and wins the queen.

Dg065: White to move Dg065: It would be tempting to play the simple QxN for free here—and erroneous. Don’t play any capture, not even of a loose piece, until it’s clear that you can’t do better. Among other things this means examining checks you can give and their consequences. White has a few with his queen; the most interesting is Qe8. Black’s king is forced to a7 (the White knight seals off b7)—and now rethink the board and ask if new tactical strikes might have become possible. With your knight so

prominently posted it is natural to look for forks it might inflict, which train of thought leads to Nb5+. White wins the queen for a knight.

forks bishop and king. Notice that Black had thought the White knight was pinned to White’s queen, but since Ne5 is a check Black has no time to take advantage of this; he has to move the king, and then loses the bishop. Another point to note: the bishop is protected by the Black knight at f6. Do you care? No, because after Ne5 the bishop also is attacked a second time by White’s queen; so if Black recaptures with NxN, White plays QxN and still is ahead a pawn. The question is not just whether a piece is protected; it’s always how many times it is protected compared to how many times it is under attack.

Dg066: Black to move Dg066: A quick color scan shows that Black has no potential forks to perfect, so start by examining every check. Here there is just one: Rxh2+. How would White respond? If he moves the king to f1 or g1, examine the resulting position: he loses his d2 rook to RxR (a skewer). So presumably he will instead play KxR. Examine the resulting board. Black’s knight will be on the dark square where it already sits; White’s rook and king will be on d2 and h2, respectively. So Black then forks them with Nxf3+ and gets back the rook (as well as the two pawns captured along the way).

Dg067: White to move Dg067: A common sort of position. Again White has no potential forks, but as a matter of course we examine every check. Here there is only one: Bxf7+. Black can reply KxB or Kd7. Then what? Redo the color scan: now White’s f3 knight, Black’s g4 bishop, and Black’s king all are on light squares. Ne5+

Dg068: White to move Dg068: Black’s king is trapped; it can't escape to g6 if it's pressured from behind. A natural idea for White thus is Qe8, preparing for the kill on h8—but Black’s bishop guards the square, so White has to look elsewhere for ideas. Start by examining every check. There is just one: Rh8. And Black has only one reply to this: KxR. Now reexamine how the board will look. White’s knight and Black’s king and queen all will be on dark squares, inviting the fork Ng6+. You could have arrived at the same conclusion by noticing that White can attack Black’s queen with Ng6 and asking whether there is any way to draw Black’s king onto the square at the other end of the fork, h8. A common way to move an enemy king onto a square where you want it is to put one of your pieces on the square, attacking the king and requiring it to move onto the square with a capture to defend itself—a decoy. Here the White rook can do the job.

KxQ). This last sequence is the most interesting one. Why?

Dg069: White to move Dg069: Start by examining the consequences of any checks you can give: our modus operandi. There are four: Ne6 (does nothing), and Qf8, Qg8, and Qh8. Qf8 can be dismissed immediately as it results in RxQ with no gain. Qg8 is unhelpful because it is met with KxQ, drawing the king to a light square; since all White has is his knight, and since the knight and Black’s queen already are on dark squares, it should be obvious that you would like to draw Black’s king onto another dark square as well. Qh8 accomplishes the mission, forcing KxQ (if the king instead moves to g6 or h6, White plays QxQ, as should be obvious if you are visualizing the White queen on h8; it’s yet another skewer). Now the White knight and the Black royals are arranged for a fork via NxR+. Another way to see this would be to start with the knight and notice from the pattern of its relationship to the Black king and queen that it is just one move from attacking either of them, but that they cannot be attacked at the same time. To achieve a simultaneous attack, one of them would need to be drawn onto a different dark square. This can be done by moving your queen to a square where you want the king to move, and from which your queen gives check (and skewers the Black queen to boot, thus requiring Black to play KxQ and walk into the fork).

Dg070: White to move Because it forces the king to move, which often creates new tactical openings. Here it results in the Black king and queen and White knight all being left on dark squares; there is a fork at f7. But wait: what is Black’s reply to 2. NxR+? He can play Ra7xN, in effect trading a rook for White’s queen and knight! The problem for White, of course, is that the forking square (f7) isn’t safe. We have ways of handling that, however: here, start by taking the piece on the forking square in some other way and see if the piece that replaces it after a recapture might then be loose. Hence White plays 1. BxR, RxB; then comes 2. Qh8+, KxQ; 3. NxR+, forking and then taking Black's queen. White wins a queen and two rooks in return for a queen and a bishop.

Dg071: White to move

Dg070: Start by examining every check you can give. There are three: BxR (leads to RxB); Qg7 (leads to QxQ); and Qh8 (leads to

Dg071: Standard procedure starts with an inspection of any checks you can give. One of them is Nc4. On a board so open you might be tempted merely to conclude that the king then gets away, but don’t be satisfied so easily; try to figure out where it will go. It’s easy

here because many of its apparent flight squares are unavailable (e.g., d4, d5, or e6). Indeed, Black has only two possibilities: Ke4 or Kf5. Now look for your next check—or, since you are playing with your knight, look for a fork. If Black plays Ke4, you have Nd2+; if he plays Kf5, you have Ne3+. In either event you win the queen next move. The important lesson is to observe how improbable a knight fork might have seemed in the original diagram given the distance of the knight from Black’s queen. It turns out that two jumps of the knight can cover a lot of ground; if the first of its moves requires a forced response from your opponent, you may end up with a fork on the other half of the board from where you began.

which it could be forked at the same time, White would have the game. Does Qh8+ accomplish this?

Dg073: White to move No; Black replies BxQ, and anyway if the king were to move to h8 it would be too far away from e6 for White to fork with his knight. What about Qh7+? The difference is that the queen would be guarded by White’s knight, which also attacks f7. Thus Black would have to move his king to f8—and into a fork. White plays Nxe6+ and wins the queen.

Dg072: White to move Dg072: Start by examining every check, however briefly. There are two. The first, Qxf5, loses the queen, so the follow-up had better be spectacular; and it isn’t. But then there is Rh6. Consider Black’s possible responses; visualize the rook on its new square. If Black moves the king out of the way—say, to g7, or g5 (taking the knight)—White wins the queen by playing RxQ (another example of a skewer). So assume Black will play KxR. Now how will the board look? White’s knight will be on a dark square, along with Black’s king and queen, which can be forked with Nf7+. So Rh6+ effectively wins the queen. Dg073: Start by examining every check you can give. There are two: Qh7 and Qh8. As you examine these, you also should notice that White’s knight can strike against the Black queen in one move—Nxe6; if Black’s king could be forced onto a dark square on

We aren’t finished. Black of course must move his king once it is forked, so press farther and ask where it will go. Moving it backward along the back rank is out, because White’s queen is there. He has to play Kf7. Does White then have any more checks? Yes; among others he has QxB—which is mate. The moral of this part of the tale is that when you have two pieces in the vicinity of the enemy king, and especially when one of them is a knight, always be mindful of the relationship between the pieces—how one can protect the other in an attack, how the knight can seal off escape squares in different directions by virtue of the odd shape of its moves, and whether the ultimate goal—checkmate—thus might be achieved. Dg074: At present Black has no forks; only one White piece is on the same color square as his knight. It might be natural for Black to consider Nh3, creating a threat of mate next move with Qf2 or Qg1. But then you think about what checks White would have in reply

and notice Qc8+—a queen fork that would win Black’s knight on h3.

you picture the outcome of the exchange you realize that it leaves Black’s king and queen on light squares, just like White’s knight; or even without that observation you simply look for your next check and observe that Ne7+ forks Black's king and queen, winning the latter.

Dg074: Black to move So Black scratches that idea and starts by examining every check of his own. There are three: Qd1, Qf2, and Qg1. Qd1 loses the queen without accomplishing anything. Qf2 forces White to reply KxQ and almost leads to a knight fork at d3, but the square is protected by White’s bishop. Qg1 also forces the reply KxQ, but it moves the king to a different dark square. Now Black can launch a fork from e2, which is occupied but unprotected; NxB+ thus wins the queen a move later.

Dg075: White to move Dg075: Start by examining every check. There are three: Ne7 (resulting in QxN; forget it), Rb8, and Rxc6. Rb8 leads to KxR, which is of no use to White; here as in the previous example, all White has is his knight, so drawing the king to a square of a different color doesn’t help. But what about Rxc6? As usual, one must actually visualize the Rook on c6 to see all the effects of moving it there. In addition to checking the king, the rook then attacks Black’s queen; so if Black moves his king, RxQ. Black thus has to play QxR. When

Dg076: White to move Dg076: You know the drill: start by examining every check. There are three to find— Nh6, Ne7, and Qg4. Start with 1. Nh6, which forces Kh8 or more likely Kg7. What check can White then play? If he tries 2. Qg4+, then Black plays KxN. So 1. Nh6+ doesn’t look very fruitful, at least on inspection of where it leads anytime soon. And Ne7+ just loses the knight. But then there is 1. Qg4+. If Black responds by moving his king, White can play 2. Qg7 and mate. Since moving the king therefore is out of the question and Black has no way to capture the threatening queen, his only remaining option is to interpose something in front of his king. He has to play Qg6. Pause to visualize the resulting position and ask whether you can do anything with it. Yes, the Black king and queen are now arranged to be forked by the White knight via Ne7+.

Another train of thought leading to the same outcome might start by observing that White’s knight on f5 attacks the g7 square in front of Black’s king, which is exposed; this suggests the possibility of mate if White can get his queen onto g7. The natural route to that result starts with Qg4, putting the queen on the right file. Black’s response is forced: Qg6. Then you see the fork.

board would look, and see that it would invite a fork of king and queen via Nf7+. Again, you might have been helped along in seeing this by observing from the start that White can attack the Black queen with one move of his knight and wondering whether Black’s king might be forced by a check onto the dark square at h8 where it could be forked.

Dg077: White to move Dg077: Start by examining every check White can give. There are four: Ng6, Nf7, Qxh7, and Rf8 (don't forget to consider every attacker). The knight checks are important because they show you that Black’s king can be attacked with the knight in just one move; they suggest that White might have a crushing fork if Black’s queen could be forced onto a dark square. Qxh7+ just loses the queen and doesn’t help the forking prospects. Rf8+, however, permits only one reply: QxR. Visualize the resulting position and see that it calls for a knight fork at g6. Ask whether the square is protected and see that the h7 pawn appears to be on the job—but it’s pinned. White wins a queen for a rook and a knight.

As noted, Black has one alternative to moving his king to h8 in response to Bd5+: he could interpose his f8 knight by playing it to e6. But if you ask what checks White then would have, you see that in addition to BxN+ he now has the better move QxN+, capturing the knight that had previously prevented him from checking with his queen. This would again force Black’s king back to h8 and allow White's knight fork on f7. (With his own knight out of the way, Black also would have the option of playing Kf8, but this leads to mate on the move for White with Qf7). The reason White should reply to 1. Bd5+, Ne6 with QxN rather than BxN is that if he captures with the bishop, Black’s move of his king to f8 works after all; there is no mating threat because White’s queen still is back on e2, stuck behind the bishop now at e6. The general point is that after administering a check and seeing a response that leaves you short of your goals, examine all remaining checks rather than rushing to re-administer check with the same piece you used the first time. Bringing your queen into your attack can be a particularly potent move, as this position shows.

Dg078: White to move Dg078: Start by examining every check. There are two: Qe6 and (less obviously but critically—examine every piece!) Bd5. Qe6+ loses the queen to NxQ. Bd5+ is more interesting. The bishop can’t be taken by any of Black’s pieces, and Black can’t move his king to h7 because of White’s knight. So Black has to play Kh8 (actually he does have one other option we will consider in a moment, but let it pass for now). Now ask how the resulting

Dg079: White to move

Dg079: Start in the usual way: examine your checks and their consequences. All the checks White has here involve its queen, which can attack the king by moving to b6, d6, c5, c4, c3, or g7. Four of those moves lose the queen on the spot, but 1. Qc4+ does not. Black can’t capture White’s queen in response, so he would have to either move his king or interpose something. Which will it be? Don’t just think of the queen moving to c4; imagine it there—and see that it also would be attacking Black’s rook, which is unprotected. Black would like to avoid the loss of his rook, and so might play Kd7 to protect it while also moving his king out of harm’s way. Now how would the board look? White’s knight is on a light square; so are Black’s king, queen, rook, and bishop—all of which can be forked from c5! The only apparent difficulty is the Black pawn at d6, which protects the needed square. But an early question about any such case is whether the protecting piece is constrained by a pin, and the d6 pawn is indeed pinned to Black’s king by White’s rook. So 2. Nc5+ wins the queen. If Black doesn't fall for this by playing Kd7 in the first place, then of course White instead uses his second move to take Black's rook. It's an example of a queen fork, which is a theme we will study in detail soon, but the general point already is familiar: sometimes a knight fork (or any other tactic) does its work without ever being carried out. The threat of it forces your opponent to cough up material to avoid seeing it executed. To put it differently, you don't play a move like Qc4+ here hoping that Black will play Kd7. It's great if he does, but you should always assume he will see the trouble coming and will play the best move available to him—probably Qc6, but in any event not Kd7. We say the sequence works here not because we fantasize that Black will play Kd7, but because you are sure to win at least a rook if he plays anything else. Alas, many of the prettiest forks never end up getting played. Going back to the main idea of the position, the tricky part is that the fork depends on the pin of the d6 pawn, which is visible only if you clearly are imagining both White’s move

(Qc4+) and Black’s response (Kd7). It is a perfect example of the importance of visualizing not only the move you imagine making but also the move that comes after it.

2.1.10. Using Multiple Checks. The skill called for in that last problem—the ability, when you examine a check or other forcing move, to keep the resulting appearance of the board clear in your mind’s eye—is one of the keys to good chess. It gets even more important as we turn to positions that require you to follow up on a first check with a second one before the fork is ready. Gradually your ability to recognize an emerging forking pattern will kick in as you are examining the checks and follow-up checks available to you. By working back and forth between forcing moves and glimpses of patterns, you build a combination. Start the following position.

Dg080: White to move Dg080: Anytime you have a battery of rooks on an open file like this, consider what would happen if you drove them both through to your opponent’s back rank. Sometimes the result may be a mating sequence there; even if not, though, the threat is powerful enough to force results—and forced results always have to be inspected in search of forks or other tactical opportunities they may create. Thus White imagines Rc8+, to which Black would reply NxR; then comes RxN+, and Black’s king is forced to f7. If you were looking only for checkmate you would have to consider the sequence a failure, since the king escapes. But

if you're looking for a tactic the sequence is a spectacular success, as it leaves Black’s king and queen both on light squares and ready to be forked with Ng5+. White wins a queen and a knight for a rook and ends up with two attacking pieces on the board against none. Notice how remote the chances for a knight fork by White appear to be on the face of this position; the knight on f3 just seems too far away from Black’s king. It’s a study in the importance of reevaluating such possibilities whenever you can make the enemy king move. A useful rule of thumb is to ask every time the king moves whether you have any new checks against it. Here that would turn up Ng5 on White’s third move.

swer with RxQ; but rather than abandon the idea, follow it through: then what check can White play?

Dg082: White to move The obvious follow-up is RxR+ (exhausting the battery on the f-file), and again the response is forced: KxR. The result of this sequence will have been the loss of White’s queen and rook in return for Black’s rook, but also—and most importantly—the movement of Black’s king to f8. Black’s king and queen would then be on dark squares; NxB+ forks them, and after winning the queen White has gained a piece (the bishop captured by the knight).

Dg081: White to move Dg081: Start by examining every check. There is only one: Ra8+. Black must defend himself. He has no way to capture the rook and can’t move his king because both of its flight squares are attacked by White’s knight. All that’s left is to interpose his bishop at d8. Now what next for White? Look for another check. Again there is just one: RxB+. If Black responds with KxR the board looks even simpler than it did at the beginning: Black rook at h8; Black king on d8; White knight on e5. The fork at f7 is self-evident. Dg082: The most natural moves to consider here might be Nxb7, picking up a pawn, or Qf7+, safely giving check and perhaps starting to hunt the king. But White can do better, and you will see this only by considering less obvious checks and their consequences. In addition to Qf7+ White also has Qf8+. This loses the queen, as Black is required to an-

Dg084: White to move Dg084: Start by finding every check White can give. There are four: Qxe6, QxB, Nf6, and Ne7. The first two lose the queen and have no good follow-ups, but Nf6+ is interesting; Black can’t respond with BxN because his bishop is pinned by White’s queen. So Black must move his king. Now ask if White will have another check after the king moves. Notice that whether the king goes to h8 or f7, White can play QxB+. Either way Black has

the reply KxQ. So then his king will be where his bishop now sits, on g7—at last on a dark square; and your knight will be on f6. Since your only plausible attacking piece is your knight, you naturally are on the lookout for a fork. In the resulting position you find it at e8. After taking Black’s queen, you’re up a bishop.

Dg086: Start by examining every check. (Again, it's drill.) There are three: Nxa7, or a move of either knight to d6. Nxa7 loses the knight to NxN without a good follow-up. Moving either knight to d6 results in BxN, but White then can recapture with another check: NxB+. With his ability to capture on d6 now exhausted, Black would have to move his king out of check to b8 or c7. Then what? You could look for yet another check using White’s bishop, with inconclusive results. Or you could notice that White’s remaining knight then would be on a dark square and that Black’s rooks both would be on dark squares, too. Nf7 forks them and wins the exchange. This time the point of the checks wasn't to move the Black king into position to be forked. It was to keep Black busy with threats he had to address while you prepared to fork his rooks.

Dg085: White to move Dg085: Your only piece that can do any checking is the queen, at g7 and g8. There is no apparent follow-up if it goes to g8 and is taken by Black’s king. But now suppose White plays Qg7 and look at the resulting position. Notice the significance of the pawn at f6; it means Black would have no choice but to play QxQ. You still are thinking in checks, so look for the next one and arrive at the natural recapture f6xQ. Again Black then has only one legal move: Kg8. Continue to be relentless in looking for the next check and you come to Ne7+—a fork of Black's king and c8 rook. White nets a rook with the sequence.

Dg086: White to move

Dg087: White to move Dg087: White has no forks yet in view, so start by examining every check. The queen has several—Qxh6, Qh8, Qg8, Qg7, Qf7, and Qe7. All of them lose the queen without creating a good fork. But there is one more check: Bxg6. How would Black respond? With KxB. Still no fork would be possible, but once the king moves you naturally reconsider the checks you can give and their consequences. (As you do it, bear in mind that the knight on d4 already can attack Black’s queen from e6, and so will have a fork if the king can be forced onto g5 or g7; this is an example of working back and forth between ideas based on pattern recognition and experiments with checks.) The interesting new check White has is Qf5—interesting because the queen attacks the king and is protected by the knight.

Black’s only legal reply is Kg7. Again, with a move by the king you reevaluate your tactical options. Now the king and queen sit on forkable squares; Ne6+ forks and wins the queen. This position is a little tricky because it takes a moment to see that White's key move (2. Qf5) forces Black's king to g7. Learning to see where the king can and can't go when it's checked takes a little practice. Dg089: White to move

Dg088: White to move Dg088: White has three checks to analyze: Qe7, Qf8, and Bxe6. The two queen checks, in response to either of which Black plays KxQ, almost create opportunities for White’s knight to fork the king and queen, but not quite; the forking square (e6) is protected in either case. So consider Bxe6+. Black's likely reply is BxB (we will consider an alternative in a moment). Now ask what checks you then would have, and you are returned to the same two queen checks mentioned a moment ago. Qf8+ requires KxQ (notice that the king can’t move to g6), leaving the Black king and queen on dark squares along with White’s knight. The forking square (e6) no longer is protected by the bishop; now the bishop is on e6. So 1. NxB+ works for White, netting a pawn. Notice the repeating pattern in the thought process involved: find a check; consider the response; look for another check, all the while keeping the changes occurring on the board clear in your mind’s eye and watching out for forks. After White's initial Bxe6, Black has another option: Ke8. But now he immediately loses another pawn to Nxd5, with more complications to follow; so BxB is less costly.

Dg089: Actually this one doesn't involve two checks, but it fits here because it does involve the search for a check after another forcing move. The trouble from the outset is that neither of White's available checks are productive (Be6+ loses the bishop; Qxd5+ loses the queen). Still, White sees that his knight is close to being able to deliver a game-ending fork at f7: there it attacks the queen and would attack the king if it could be driven into the corner at h8. Since checks don’t seem helpful in producing this result, White considers the next prominent way of forcing changes on the board: captures. The most prominent piecefor-a-piece capturing possibility is BxN, which leads to h7xB. The important question about such an exchange, of course, is what does it leave behind? What open lines? It opens the h-file, so ask anew what checks are possible and with what consequences. There is a fresh one: Rh8+. Black has to play KxR in reply (White’s knight guards the king’s flight square at f7); the check at h8 sucks the king onto that same square. So now the king has moved, and whenever that happens you ask what checks have become available—especially given that the knight has been waiting to administer a fork at f7. Indeed, Nf7+ is White’s only check then remaining. It wins the queen. (Black moves his king, and White plays NxQ. Now Black recaptures BxN; and if the Black move of his king was to g8, then White now has the queen fork Qxd5+.) What all this means is that the original BxN wins a piece, as Black cannot afford to recapture h7xB. As we have seen, that often is the significance of seeing a fork: not that you get to play it, but that you are

able to make material gains because you realize (and your opponent realizes) that if your captures are avenged by your opponent he ends up the victim of an even worse double attack. Incidentally, it might have occurred to you that Black could reply to White’s 1. BxN with 1. …QxB, but this is worse. The problem for Black is that White then plays 2. Qxd5+ (again, always looking for the next check) and now has tremendous pressure against the Black king's position. The pressure may not result in immediate mate, but it produces heavy casualties: (a) If Black moves his king to h8, White has 3. Rxh7+, which requires the Black queen to take the rook on h7 (the king can't move)— and then the queen gets taken by White’s knight: 4. NxQ. (If Black recaptures KxN on h7, White has a queen fork: 5. Qh5+, which wins the rook on e8 and leads to mate soon after. This last kicker might be hard for you to spot, because you have to see that by the fifth move the White queen would have clear paths from d5 to h5 and from h5 to the rook on e8. But just seeing that Black loses his queen is enough for now. (White also can do at least as well—maybe better—by playing 3. Nxh7, but let that pass for now; it's more complicated..) (b) If Black instead replies to Qxd5+ by moving his king to f8, White has Nxh7+ and Black again must sacrifice his queen with QxN to put out the fire. (If Black instead replies to Nxh7+ by moving his king over to e7, White plays BxBc5+; now Black’s only legal option is to interpose his queen on d6, losing it next move and getting mated soon after.) There are some other possibilities, but White does pretty well in all of them. White also does nicely by starting with Qf3, but that's a tale for another time. Some of those variations sketched a moment ago take a little time to see. The trick to them is to think relentlessly about what checks White might play in response to each of Black’s moves.

2.1.11. Using Mate Threats to Force Pieces into Position. Now we're going to consider a few positions where the elements of a fork are brought into being by a judicious use of mating threats. These studies will be pretty hard, at least by comparison to those we've seen already; peruse them for the ideas involved. The whole question of the tactical use of mating threats will be explored in more detail, and in a more step-by-step fashion, in the next chapter (on queen forks).

Dg090: Black to move Dg090: Prospects for a knight fork for Black might seem remote in the position to the left, but it turns out to be easily accomplished. Begin by thinking about the enemy king and any pressure you can put on it. Ng4 is interesting because it seals off f2 and (more to the point) h2, leaving the White king trapped on the back rank just as it would be if there were a wall of pawns in front of it. You look for the follow up and see that Black would then be ready to mate with Ra1+ (White would have the useless interposition Rd1, to which Black replies RxR#). Now of course after Black plays Ng4 White has a move he can use to fend off the coming Ra1+; he plays Rd1, thus preparing to meet Ra1 with RxR. What now for Black? Anytime your knight is in the picture and enemy pieces have moved, consider forking possibilities. From g4 the knight would be able to jump to f2 with check and take the rook for free next move. The trick to the position is to carefully look not only for any checks but also for any mating threats you can create - not necessarily

because you expect them to lead to mate, but because you know they can create pressures that have tactical payoffs. A search for mating threats includes consideration of any move like Ng4 that, while not giving check, traps the enemy king in a tight space. Then you figure out what your opponent would have to do to defuse the threat, and ask whether any forks or other tactical moves would be possible on the board as it then would look.

Dg091: Black to move Dg091: This position closely resembles the last one; but here each side has an extra piece, and the one that matters is White’s bishop on c7. Now if Black tries the same beginning move discussed in the prior position—Ng4— White has a better way than Rd1 to fend off the threat of Ra1#. He can instead play Bb6, preparing to meet Black's Ra1 with Bg1, which would effectively block the check. So Black needs another idea.

does move his king to h2, another dark square, Black can skip Rh1; instead he wins a rook with the knight fork Nf1+. (b) White’s other option in reply to 3. …Ne3 is to step his g3 pawn forward to g4, giving the king a flight square to the side. Now Black plays 4. …Rh1 and White has 5. Kg3. Again, though, this puts White’s king onto a dark square and allows Black to win the rook with the knight fork Nf1+. This whole sequence also was available in the previous position; if you saw it there, great. The point is that here you would have to use it. The shorter fork described in the previous frame no longer works. In a sense, though, the lesson of this position is the same as in the prior one: think about checks and mate threats you can create, not just on the board in front of you but also on the board as it will look after a check or two or after some other set of forcing moves. Here this means seeing 3. …Ne3, which doesn’t give check but does threaten mate and so forces White to choose between two moves that each lead him into a fork. When your knight is hopping around as Black's does here, you especially want to think about forking possibilities at every turn; 3. …Ne3 not only creates a mate threat but also puts the knight on a dark square along with White’s rook, meaning that Black can fork the rook if White’s king steps onto one of its available dark squares as well—as it soon must.

The natural alternative to explore is an immediate 1. …Ra1+, forcing White’s king to h2. Black then looks for his next check and finds 2. …Ng4+, forcing the king up another square to h3. Now watch this: Black plays 3. …Ne3—not a check, but renewing the threat of mate via Rh1 since the knight now seals off g4 and keeps the White king trapped on the h file. White somehow has to find an out for his king. Moving it to h4 won’t do; that still leaves no safe square after Black plays Rh1. But White has two other choices. Dg092: White to move (a) The first is Kh2, readying the king to capture the rook if it moves to h1. But keep track of the Black knight’s position: it has moved twice and is on e3, a dark square. If White

Dg092: White has limited resources, but one of them is a knight on e5 that can give check with Nxf3 or Nxg4. Those checks are of no

use now, but they're important to see because they mean the knight is poised to deliver a fork if one of Black’s pieces can be lured onto another square that the knight is able to reach from f3 or g4. Another way to put the point is that any other squares the knight can reach from f3 or g4 may now be very safe for White to occupy with one of his other pieces (he would be happy to see Black perform a capture there and walk into a fork). Since White only has one other piece, a rook, the natural thing is to experiment with places it can go that take advantage of this forking potential. There is one such square: f6. If Black replies to 1. Rf6 with QxR, he gets forked with Nxg4 and loses his queen. Well, so what if Black doesn’t play QxR? The first way to explore that question is by asking what checks you next would have—and seeing Rh6, which turns out to be mate. (Notice how constrained Black’s king is.) So actually Black does have to play 1. …QxR to avoid the mate threat, and this results in the aforementioned knight fork. Once you understand White's mating idea here, it might occur to you to start instead with 1. Rxg5. This, too, puts White one move away from mate on the h-file (with Rh5). When you look for ways Black could fend off the mate, you see Qh6—and realize that this would arrange Black's king and queen to be forked with Nxg4+. Indeed, this achieves the knight fork without giving up a rook at the beginning, so at first blush it looks better than the brazen Rf6. But there is a catch. Are you sure Black would walk into the fork by replying to Rxg5 with Qh6? Rxg5 is a formidable threat, but it isn't a check, so Black has some freedom in replying to it. Consider not only Qe8 but the possibility that Black can go on the offensive with Qb6+. White is pretty much forced to play his king to e1 (Kf1 results in Qg1#). And then Black holds the initiative with another check: Qe3+—and notice that this is a queen fork of the rook now on g5, which White is about to lose. And then White has to worry about the Black f-pawn promoting, and will have to sacrifice his knight to stop it. (Starting with Rf6 avoids the mess just described because it puts the rook

on the sixth rank, allowing it to reply to 1. ...Qb6 with 2. RxQ.) So the short of it is that starting with Rf6 wins the game for White; Rxg5, which looks safer, loses it. To reiterate the crucial train of thought, you might overlook the resource Black has in 1. ...Qb6 by focusing too much on how he can defend against mate, since from that perspective Qh6 does seem to be his only move. The key, again, is to ask not just about defense but about what counterthreats Black might try, and especially what checks he can give (Qb6)—and then what further checks (Qe3 or Qg1). That's the biggest difference between working with checks and working with mate threats: they both force your opponent's replies to some extent, but the mate threat gives him the option of seizing the initiative if he can find a way to do it; so you must ask if he can. Going back to the original idea, of course you might have seen it not only by thinking about your knight check but also by starting with the stuckness of Black’s king; it has no safe escape from the h-file. This makes you think of putting a rook onto the h-file, but it’s hard to get it there because Black has a queen positioned to defend against any such effort. Yet for the sake of argument you go ahead and imagine 1. Rf6, QxR—and then see that this puts Black’s king and queen both on dark squares, enabling them to be forked with Nxg4+.

2.1.12. Strategic Implications. Your first question before making almost any move is whether there is a tactical opportunity for you on the board. If there isn't—as routinely will be true—then your choice of move will be determined by strategic considerations: attempts to secure positional advantages that may ripen into tactical opportunities. One goal of strategic play is to create the types of positions where tactics, such as the double attacks we have studied, become possible. It is not the purpose of this site to advise you on effective strategy in any depth, but here are a

few elementary points on the subject, particularly as it relates to the knight. A couple of general things first. It often has been observed that good positional play leads naturally—perhaps even mysteriously—to chances for tactical wizardry. Why? The reasons have to do with what good positional play accomplishes. The most important purpose of it is to expand the power and mobility of your pieces—often the same thing, because the power of a piece largely is a function of how many squares it attacks, which in turn will depend on its mobility. A rook on an open file—i.e., a file containing no pawns—is very mobile and for that reason very powerful. Likewise a bishop on an open diagonal. So when you look at a piece and assess the quality of its position, consider how many squares it controls. A fully deployed army of pieces will attack a large share of the squares on the board, especially including squares in your opponent’s half of the board, many of them two or three times. A second purpose of positional play, of course, is the converse: limiting the power and mobility of your opponent’s pieces. The fewer the squares he attacks, the greater your ability to put your own pieces there. These principles relate to tactics in obvious ways. If your pieces have lots of room to move and attack lots of squares, that means they can range more boldly into parts of the board where they can cause trouble to your opponent; it also means you are more likely to be able to coordinate them, bringing two or three or four pieces to bear on a sector in ways that permit a combination: perhaps sacrificing one, pinning with the other, and then capturing or forking with the third. Note that an individual piece does not threaten much when it ranges into enemy territory by itself; as we have seen many times, a knight usually needs help from other pieces to set up a good fork. Meanwhile if your opponent’s pieces are constricted or blocked in their movements, this does more than prevent them from causing you trouble. It makes them prey to tactical strikes, because they give him fewer good options in responding to checks, captures, and threats that you make.

So when you aren’t playing tactics, think about these two considerations: how you can place your pieces to enlarge the amount of territory (“space”) they attack and control; and how you can place your pieces and pawns to confine your opponent’s army. This partly is a matter of simple gestures like moving your rooks onto open files, getting your knights and bishops off the back rank and out where they can exert pressure down the board, and keeping a pawn or two in the center so that your opponent can’t plant pieces there and so that your pieces there are protected. It’s also a matter of subtler things: exchanging pawns where the exchange will create an open or half-open file for your rook (but perhaps not if it creates such files for his rook); placing your pawns (and keeping his pawns) on squares that block the paths of his bishops; and thinking about how pawn moves and exchanges affect the lines open to other pieces on both sides. These are general ideas to consider when you are picking a move without any immediate tactical purpose. Against this backdrop consider the knight in particular. The knight doesn't need open lines because it jumps rather than slides. But it still needs help from your pawns to be effective. The first thing to grasp is that the knight’s prospects for creating mischief tend to increase as it moves up the board. A White knight on f3 early in the game serves mostly a defensive purpose, and a valuable one (though of course even this knight has offensive potential, as we occasionally have seen); the same knight on, say, d4, d5, or d6 becomes a terrible offensive threat. On d6 it strikes out at eight squares, including six in your opponent’s half of the board; from any of the squares just listed the knight can attack the opponent’s back rank, and often his king, in one move. (More than 90% of the knight forks we have considered involved the king as one of the two targets.) So an important general strategic aim is to get one of your knights planted on a square on your fourth rank or beyond. An especially good place to plant a knight is on a square near the center, since from there it can make threats and influence play in all sectors of the board. This is why chess books often speak of the importance of

controlling the center, and of the battles that players wage to keep a pawn on the central squares and to keep enemy pawns away from there. The point is not necessarily that pawns in the center themselves threaten anything; it is that the pawns control the squares that they can attack. When you have a pawn on e4 it controls not e4 but d5 and f5. Enemy pieces are unable to move to those squares; your pieces can. Having good central squares on which you can plant your pieces is important. That is where they are most powerful.

Dg093: White to move Dg093: The key word is “plant.” It’s not much use to move your knight to a central square only to have it chased away by a pawn. You have to create a hospitable square - an “outpost square”—for your knight. A good outpost (d5 in the diagram) is a square where the knight cannot be harassed by pawns, because the enemy pawns on either side of its file are gone, are blocked, or have advanced up to your knight’s rank or beyond it. Ideally the well-posted knight also is protected by one of your own pawns; that will prevent it from being chased away by one of your opponent’s rooks or his queen. The remaining point is to make sure the knight is not threatened by one of your opponent’s bishops or knights. The White knight in the diagram has all of the good properties just described. It is planted in the center of the board on d5, where it has two ways to check the Black king. So long as the knight stays where it is it will be a constant forking threat, exerting a great influence over everything else that happens in the game. Notice the role of the pawns here: White controls the knight’s square with the pawn on e4; Black has no pawn that can chase the knight away—and also no knight,

and no light-squared bishop. As a result, the knight probably will be impossible for Black to dislodge without a sacrifice. White had to fight to create this position; for an account of the battle, see Weeramantry’s first-rate book Best Lessons of a Chess Coach. The conditions of a good outpost square may seem numerous, but creating them is a suitable task to keep you busy when you aren’t playing a tactic. Some of them take care of themselves; others require work. Realize, first, that every time you move a pawn forward you weaken the squares it used to protect. If the pawns on either side of a square have moved forward or are off the board, the square becomes a hole where the other player eventually can put his pieces, comfortable in the knowledge that no pawn will be able to chase them away. It is common for such holes to be created inadvertently as each side advances and exchanges pawns. (In the diagram here, Black allowed a hole to be created on d5 by moving his e-pawn to e5 and by allowing his c-pawn to be removed.) This is a critical consideration to bear in mind both offensively and defensively. From an offensive standpoint, realize that the most important consequence of an exchange of pawns (or of any sequence) sometimes can be to foul up your opponent's pawn structure and leave holes behind. On the defensive side, think carefully about whether your pawn moves or exchanges will result in holes that create outpost squares for your opponent’s knights and other pieces; place your pawns so that they guard (rather than occupy) the attractive squares where his knights might like to perch. A few pawns well-placed in this way can neutralize a knight quite thoroughly. As for your opponent’s bishops, if one of them is off the board, then squares of the color the missing bishop used to patrol are natural candidates for outposts. Likewise, if you see a promising outpost square it is worth hunting down and exchanging away the enemy bishop that travels on squares of that color. If you then have to move a knight three times to get it onto a good outpost square, it may well be worth it. A knight often will not be a big factor in a game—and will not be

able to make the types of moves seen in this chapter—unless it finds a suitable outpost; once it does find an outpost, it may dominate the rest of the action. Even if you cannot satisfy all of these criteria for an optimal outpost square, taking care of one or two of them— creating the characteristic pawn structure in particular—may create an outpost that is suitable for quite a while. (If you can’t get rid of the bishop on the color of the outpost square, for example, it may nevertheless be out of position to do anything about your knight.) And naturally a safe outpost may be easier to create later in the game when there are fewer enemy pieces on the board.

2.1.13. Summary. The natural tendency of the mind when looking at a chessboard, as elsewhere, is to jabber away with tangled thoughts. Effective chess requires a different style of thinking: systematic, thorough, and aggressive. You want to ask the right questions before you decide what to do. There are, first, general questions that must be considered routinely. As the great Australian chess writer Cecil Purdy suggested, the most basic are “what does he threaten?” and “what is his reply if I make this move?” Also, and relatedly, “if I do this, will I leave anything unprotected?” and “does he have any checks that can cause me trouble?” There is no need to blunder away a piece by leaving it unguarded if you are careful to interrogate the board this way as a matter of course. The principles laid out in this chapter might likewise be summarized into a sort of checklist. The goal of studying patterns is to internalize all this and think with your eyes, rather than in a verbal flow chart, but as you are getting started it helps to dwell on the questions that are helpful to ask yourself, with or without words, before deciding what move to make. With respect to knight forks, the important questions generally arise when you have a knight in the same vicinity as some of your

opponent’s pieces, and especially within striking range of his king. Again, the order in which the questions are asked is not particularly important, and will depend on the salient features of the position that suggest themselves to your eye; nevertheless, the ones most often important are these: Do I have a potential fork? If so, Is the square that I need protected? If so, Is the protecting piece constrained? Is it pinned, can it be pinned, or would it be pinned after the sequence of moves I am considering? Can the protecting piece be captured, and then be replaced with a piece that is less effective? Can I capture something that the protecting piece guards, thus luring it away from the forking square? If there is no immediate way to do this, are there any sequences of exchanges that would have this effect? Can one of the pieces in the fork be captured and thus exchanged for a more suitable target? If I go ahead and deliver the fork and let my knight be captured, what then becomes possible? What lines are opened, and what pins created? What checks could I then administer, and with what replies? Then what checks or forks would I have? If I don’t have a potential fork, can my knight check the king? If so, can a valuable enemy piece be moved onto a square that would be forked by my check? If my knight can't give check, what checks with other pieces now are available to me? What are the responses required by each of them? What checks could I then add, and with what responses? Do the positions resulting from any of these sequences create chances for knight forks? Let this chapter change the way you think about checks and captures. Very often they are usefully given not for their own sake but because they require responses that change the board and may then create good opportunities for double attacks or other tactical

strikes. So when you imagine making a capture, do not just ask whether your opponent can recapture and write off the idea if he can. Imagine what would be possible after your opponent recaptures that might not have been possible before. By the same token a check that easily can be evaded hardly is worthless for that reason; the point of a check commonly is to force the king to move or to force other responses that eventually might make a fork or other tactic possible. This basic principle—viewing checks and captures as ways of changing the look of the board to create other opportunities, rather than as ends in themselves—is the essence of tactical thinking.

2.2. The Queen Fork.

2.2.1 Introduction. Double attacks by the queen, like all others, have certain repeating characteristics that follow from the value of the piece and the types of moves it can make. Every chess player knows to value the queen because of all the different ways it can move. As students of tactics in general and double attacks in particular, however, we can see the queen’s value more precisely: purely as a matter of geometry, the queen can attack any two squares on the board at the same time; if you put the enemy king on one square and another enemy piece on another square, there is always a third square from which your queen can, in principle, attack them both. (In the skeletal diagram to the left, White’s queen forks Black’s king and rook.) We say “in principle” because often the needed square will be unreachable or protected, or the lines from the square to the king and loose piece may be blocked by other pieces. But it is worth reflecting anyway on this feature of the queen’s power. It helps explain why the queen surpasses all other pieces as a tactical weapon. As a double attacker it has no peer. The queen’s immense usefulness also limits its power in this respect: it generally is too valuable to trade for any other enemy piece on the board. Of course the queen sometimes may be sacrificed to achieve checkmate; you may exchange queens, if the other is more dangerous than yours; and very occasionally you may give up your queen in return for a large number of your opponent’s other pieces. But usually it isn't worthwhile to use your queen to take an enemy piece that is protected. Either the protection has to be eliminated or a different, loose target has to be found. Notice the practical implication: usually at least one loose (i.e., unguarded) enemy piece must be found or created for a queen fork to be effective. This principle—the requirement of a loose piece—does not apply to knight forks, because if a knight attacks a rook or queen it makes no difference whether they are defended; you gain just by exchang-

ing, because knights are less valuable than those other pieces. We can go farther. When your queen inflicts a double attack, the enemy will have time to move one of the attacked pieces; if neither of them are his king, he usually will move whichever is unprotected. That means that to be effective a double attack by the queen usually has to attack either two unprotected pieces or an unprotected piece plus the king; for only then will there still be an unprotected piece left behind for your queen to capture after your opponent moves the more valued or vulnerable target of the fork to safety. Attacking the king here has all the advantages that it did when we studied knight forks: the opponent must attend to the threat, usually by moving the king or interposing something, thus leaving the other piece being forked to get taken. (An additional possibility we will consider, almost as good as attacking the king, is threatening mate. This less often is an issue for the knight than for the queen, because the knight less easily can make such threats.)

Dg094: Black to move Dg094: Here, then, are the key points to guide your hunting: the targets for a double attack by a queen usually include (a) the king— either by a check or by a mating threat, and (b) an unprotected knight, bishop, or rook. You are looking for squares from which your queen can attack two of those targets, or where it might be able to attack them after some preliminary maneuvers. From this we can deduce a fairly manageable set of challenges to making queen forks work: the forking square is guarded; the line to the forking

square is blocked, or the line from the forking square to one of the targets is blocked; the king is not yet in position to be checked, but can be brought into position; there is not yet a loose piece at the other end of the fork, but a piece there can be loosened or an already loose piece can be forced there by threat or attraction. In the next sections we will study how to identify and solve each of these problems. The solutions to most of them involve exchanges.

2.2.2. Simple Cases: Forking the King and a Loose Piece. We start with simple positions where the queen is one move away from inflicting a double attack. Even if you are new to queen forks you may be able to see the solutions to many of these right away. It’s still worth studying them methodically so that your grasp of the principles involved will be clear when we move to more complicated cases. For other readers double attacks with the queen may be hard to spot at first; in the beginning the board will look like a sea of pieces and squares, with the queen coming out of nowhere to attack two targets. But in fact most double attacks with the queen follow recognizable patterns, and these simple positions will enable you to nail down their fundamentals before worrying about how to remove obstacles to their execution. In each position your task is to find a square your queen can reach and from which it will (a) check the enemy king and (b) attack a loose enemy knight, bishop, or rook. So you might begin by finding the undefended enemy pieces on the board. Think of this as a basic and ongoing part of your job during a game; every loose piece is a potential target you might be able to take for free with a double attack. Next, look at any checks available to your queen. Sometimes this will be easy, but more spectacular double attacks often require you to notice checks possible from counterintuitive squares. It is good to be exhaustive.

Think of it this way: the queen can move in both directions on the rank where it sits, on the file where it sits, and on each of the two diagonals where it sits. So it has a maximum of eight available paths. Be aware of its possible movements along each of them, asking if any squares it can reach would provide it with an open line to the enemy king—and whether any of those same squares also provide it with an open line to a loose enemy piece. In practice you can disregard some checks very rapidly, but as you are learning about forks you are better off erring on the side of being thorough.

Dg096: First observation: White’s rook is unprotected. (So is his queen, but it’s a harder target to go after.) Second observation: in Qd4, Black’s queen has a safe check that attacks White's rook. So there is the idea of the fork. But then you also want to make sure White can't wriggle out of it. His natural idea would be to try to move the rook away and block the check all in one move with Rf2. So suppose he does; how do you figure out whether this reply spoils your idea? Ask the cardinal question: consider what your next check would be, and with what consequences. Here it's Ra1, which forces White's king to h2. His rook has been left loose, so Black takes it: QxR.

Dg 095: White to move Dg095: The example is as simple as the pattern gets. Again, you are looking for two things: unprotected (“loose”) Black pieces, and moves by White that check the Black king. The idea is to combine those ingredients to create a double attack. Black has one unprotected piece: the knight. White has one way to check the king: Qd8. That move also attacks, and collects, the knight after Black spends a move relocating his king to h7.

Dg 097: White to move Dg097: Look for unprotected Black pieces and you find the rook at g5. Look for checks White can give with his queen and you find two: Qd8 and Qxg7 (be careful not to overlook a check just because the needed square is occupied by an enemy piece). Qd8 is the winning move; it checks the king and also attacks, and wins, the rook.

Dg096: Black to move Dg098: Black to move

Dg098: What White pieces are unprotected? Both rooks. What checks does Black have? Might as well be thorough about it: QxQ, Qxe3, Qf3, Qg4, and Qxg2. Do any of those also attack a loose rook? Yes, Qxg2; it wins the rook on h1 after White moves his king. This example illustrates the importance of habitually noticing checks on squares like g2 where enemy men currently sit.

(b) Goal #2: be conscious at all times of any checks you can give. Here there are two: Qd3 andQc2. (c) Goal #3: look for any ways a check can be combined with an attack on a loose piece. Here Qc2+ attacks and wins the bishop.

Dg101: Black to move Dg099: Black to move Dg099: You are looking for unprotected enemy pieces and for checks, hoping to link them for profit. Scan for unprotected White pieces and you find the knight (as well as the queen, but again the knight makes a more feasible target for a fork). Now look for checks, and in particular for a match—a check that also attacks the loose knight. Qf5+ or Qf1+ work (it’s important to see both, since they may have different side consequences), attacking both knight and king, and winning the former after the latter moves.

Dg101: Search carefully for loose pieces and checks. White has one piece that is unprotected: the rook at a2. Black has three checks: Qe8, Qe6, and Qe4. You can match a check with an attack on the rook with Qe6+; and e6 is unprotected. Black wins the rook.

Dg102: Black to move

Dg100: White to move Dg100: (a) Goal #1: be aware of loose pieces on the board at all times. The Black bishop at c6 fits that description.

Dg102: Does White have any loose pieces? Yes, the rook on d7. How many checks does Black have? Three: Qe2, Qd1, and Qb5 (examine the queen’s movements on every axis open to it—vertical, horizontal, and diagonal). You ask whether the queen can attack the rook from any of those squares, and see that it can do it from d1 or from b5; but of course at d1 the queen is unsafe, as it gets taken by the rook. So Qb5+ is the winning move.

cially on an open board like this, whether your opponent might be able to move his loose piece out of danger and block the check at the same time. Here White can do this with Rh2. Does this scotch the idea for Black?

Dg103: White to move Dg103: Black’s rook is unprotected and so makes a fine target. Now you look for queen checks available to White and find many on this open board: Qd7, Qb7, Qb4, Qg5, Qc5, Qe8, Qe5, and Qe2. But we are only interested in checks that also attack the Black rook, and from a square that the rook cannot attack. Qe2+ works—a study in the importance of considering backward moves as well as the more obvious attacking moves that push your pieces toward your opponent’s end of the board.

Dg104: White to move Dg104: Now a defensive study. White is about to play BxN, which looks safe. But consider the board as it would appear after the capture. Ask what White pieces would be left loose and you find the bishop then at b3. Ask what checks would Black have, and especially any that also would attack the bishop, and you find Qb6+, which would win back the lost piece after White moves his king. Dg105: Look for checks; look for loose enemy pieces; put them together with Qh7—a queen fork that appears on its face to win the rook at c2. But always you have to ask, espe-

Dg105: Black to move No; he persists in looking for his next check and sees that Qb1 would then be mate. (Notice how cramped the White king’s position becomes once the rook is on top of it; the Black king at f3 is doing valuable work cutting off flight squares. These cues suggest the importance of looking carefully at the effect of any attacks you can make against Black’s king.) So if White is alert, Black’s queen fork wins the rook on c2 after all. If White isn’t alert, he is mated. It’s a study in the value of always examining your next check and its consequences, even if the result of the first one you saw was disappointing.

2.2.3. Using the Side of the Board During the Opening. Before examining some complications, let's focus for a moment on one type of simple queen fork that often arises early in a game: the move of a queen from its original position to the side of the board, where it may be able to check the enemy king and also attack a loose piece in the center. First we will look at a couple of elementary examples to illustrate the idea; then we will examine what the pattern can look like from a defensive standpoint just before it arises.

Dg106: White to move

Dg107: Black to move

Dg106: In this first example, examine the protection each Black piece enjoys and notice that both rooks and (above all) the knight are unguar-ded. Now ask what checks White’s queen can administer and what else it can do at the same time. You see that it can attack Black's king by moving to a4, and that from there it also attacks and wins the loose knight.

Study the pattern of open squares on the d and c files here so that it is visually familiar to you.

This is a classic pattern. A queen from its starting position on the board often can check the enemy king by jumping to the a-file or the h-file, so long as the pawns blocking its path—first its path to the side of the board, and then its path to the enemy king—have been moved out of the way. The key squares to monitor are the c2/d7 pair and the e2/f7 pair for White; if either of those sets of squares have been evacuated by their pawns, the White queen may be able to check the enemy king with one move and simultaneously attack a loose piece near the center. Likewise the c7/d2 and e7/f2 pairs from Black’s standpoint. When you see these pairs of squares open up early while the enemy king still is in the center, think hard about any moves or exchanges that would leave a piece unprotected in the middle of the board, or that would leave a piece there attacked once and protected once. Dg107: Now the same idea from Black's side. White has just made a capture that left his knight loose in the middle of the board; he thought the e5 square looked safe. But with the d2 and c7 pawns both moved, see how Black’s queen can check the White king and attack (and win) the loose knight with one move: Qa5+.

Generally speaking, the most striking early tipoff that a move like this may be possible is the movement of pawns on the c or f files. Movement of the d and e pawns early in the game is common; early movement of the c or f pawns is a little less standard, and so should jump out at you as creating the possibility of moves like we see here.

Dg108: Black to move Dg108: Here is a study in caution. White just played the pawn capture d5xe6. Black must respond; but how? The important thing to notice is that White’s c and e pawns have moved, creating open diagonals for his queen. If Black’s f-pawn moves (to play f7xe6), the White queen suddenly will be able to check the Black king by moving to h5; if Black plays Bxe6, White’s queen can check with Qa4. The reason this matters, of course, is that Black has left a piece loose on a5. So Black mustn’t play f7xe6—as he did here, losing the knight to the queen fork Qh5+. He is better off using his d7 bishop to take the pawn on

e6; for then if White tries a queen fork on the other side—Qa4+—Black can both move his knight to safety and block the check with Nc6. This is a common way that a goodlooking queen fork can be spoiled: the forked piece moves to block the check, and suddenly both threats are gone. Another way to see this, naturally, would be to start by keeping tabs on Black’s loose pieces. Here he has a loose knight on the fifth rank. Loose pieces on the middle ranks often are vulnerable to double attacks of this type by the queen, especially early in the game; in view of this vulnerability, Black should think carefully before opening any fresh lines to his own king. White can treat the situation as an opportunity; in effect Black's f7 is subtly pinned in place, since if it steps forward White has a queen fork. Incidentally, f7xe6 also would be a weak move for Black on strategic grounds. It weakens the pawn cover on his kingside, where he might want to castle; and it creates a little pawn island—an “isolated” pawn with no fellow pawns on the files to either side of it— that will have to be protected by a Black piece from now on. Dg109: Another study in due care. Black has just played Nf6, resulting in a common position four moves into the open Sicilian defense. White’s e-pawn now is under attack and is not protected. White has to do something; but what?

Dg109: White to move One possibility is to push the pawn to e5. This might seem attractive because it advances

White’s center and attacks Black’s knight, forcing it to move. But first you need to notice that White’s d-pawn and Black’s c-pawn have been moved—a normal state of affairs in this opening. This means that Black’s queen is one move away from being able to both check the White king and attack any White pieces on the fifth rank, which White must therefore regard as a zone of great danger. Playing e4-e5 thus is a mistake because it leaves the pawn loose; it will be taken a move later by the double attack Qa5+. White should instead protect the pawn with Nc3.

Dg110: White to move Dg110: More exercise in avoiding trouble. It’s early. White has moved a pawn and one of his bishops; Black has just made c7-c6 his second move. What should White play? The important thing to notice is that now the White d-pawn and Black c-pawn both have been moved. With Qa5+ the Black queen can check the White king and also attack anything on the fifth rank, such as White’s loose bishop. White should protect the bishop or block the queen’s path to the king with a move like c2-c3. If White instead plays e2-e3 here, naturally Black replies Qa5+, winning a piece. Notice, by the way, that in the position as diagrammed Black would not quite be ready to win anything with Qa5; the move is a queen fork, but White has a solid response in Bd2 or Qd2, either of which both blocks the check from a5 and gives protection to the bishop. It is a regular part of considering a fork to ask whether both prongs of it can be blunted by a single move like one of these. But if White plays his pawn to e3 those de-

fensive moves no longer work because he has obstructed the path from his bishop to the d2 square. Study the visual appearance of the Black queen’s path here—the elbow-like pattern of open black squares leading from its position to the White king. It's something you never want to overlook. You also can treat this as a case study in the danger of leaving pieces on the board that have no protection but that seem safe because nothing is attacking them. They are prey to forks. The sight of White's bishop sitting out on g5 like this, bereft of protection, should make you edgy.

Dg112: A last example of the defensive implications of our current theme. Black just played c5xd4. If White plays Nxd4, the natural recapture, his knight and bishop are poised to be forked by Black’s e-pawn. (We will study this pattern closely in the chapter on pawn forks.) Perhaps White shouldn’t worry about this, because if Black plays e7-e5, White can just play Bxe5. Or can he? Again, White should not play in the middle of this board without noting that White’s d-pawn and Black’s c-pawn both have been moved. That means anything White leaves on the fifth rank at the end of an exchange is likely to get taken in a fork by Black’s queen. Bxe5 indeed would have that effect, losing the bishop when Black plays Qa5+. So White would have no good answer to the pawn fork e7-e5, and dares not play Nxd4 in the first place.

Dg111: White to move Dg111: Black has just played e7-e5. The pawn he has left on e5 has no protection, so White appears to be able to take it for free with his knight. Again, however, notice that the move would leave the knight loose. Notice also that the Black queen can give check with Qa5 and at the same time can attack the fifth rank. So White must not leave any pieces loose there; Nxe5 would lose the knight to Black's queen fork a move later.

Dg112: White to move

Dg113: Black to move Dg113: Play began 1. e4, e5; 2. Qh5. Now what should Black do? White’s last move is not quite comparable to the forking moves the queen made in the previous examples, because here the queen does not have an open line from the h-file to the enemy king. But danger lurks nevertheless. One way for Black to chase away the queen is to play a pawn to g6. The move fails to protect the e5 pawn and is poor for that reason alone; but more importantly, ask the question White will be asking himself after that move: what checks will he have? Qxe5+—which also attacks and wins the unprotected rook on h8, the line to which would have been opened by Black’s last move. A simple move to protect the pawn on e5, such as d6 or Nc6, was indicated for Black.

Black’s bad second move is unlikely to occur in any actual game you play (nor is White's second move, Qh5); this position is given just to illustrate the damage a queen can do after it has moved to the side of the board and then is given a chance to move to the center. We will see a more involved example of this pattern later in the chapter.

2.2.4. Making the Forking Square Available. Now that you are familiar with simple queen forks, consider a first way they can become complicated: the square you need—the forking square—might be protected. “Protected” does not mean there is an enemy piece on the square, of course; it means there is an enemy piece attacking the square—perhaps defending a piece that sits on it, or else just protecting it while it is empty. In either case, here just as in the chapter on knight forks we will see that an exchange often eliminates the problem. Perhaps the defender itself can be captured; perhaps the piece sitting on the square can be captured, so that when its defender recaptures the square is left unprotected (with its former guardian now sitting on it); or perhaps the defender can be lured away by capturing another piece it protects or making a threat (e.g., a check) that requires the guardian’s services elsewhere. Since the basic theme is familiar from the chapter on knight forks, we will look more briefly at examples of how it works here.

Dg114: Examine the position using the approach already established: look for ways to combine a check with an attack on an unguarded enemy piece. Here you see that Qd5 gives check and also threatens the loose knight on a5. But before you make the move you also have to ask whether—and how many times—the needed square is protected. In this case it's guarded by the knight on f6. So: do you have any pieces attacking the knight? Yes, the bishop on g5. The idea behind the resulting sequence is familiar from the chapter on knight forks: 1. BxN, QxB; 2. Qd5+, and White wins the knight.

Dg115: White to move Dg115: Black has one loose piece: the rook at h7. White has one check with the queen: Qg8, which also attacks the rook. It all looks fine except that Black guards g8 with his knight. So press forward with the next question: Does White have any pieces attacking the knight? Yes, the bishop at c5 and the knight at f5. (The two attackers are important; do you see why?) Thus 1. BxN (or NxN), and after Black's recapture, g8 is available for the White queen to administer the fork. The answer to the question about the two attackers is that the double attack would be foiled if Black could recapture on e7 with his king; for then White no longer would be able to give check with Qg8. But Black's king can't make the recapture because whichever piece White uses to capture on that square is still protected by the piece he didn't use.

Dg114: White to move

Dg116: Notice the checks Black has with his queen: Qd1, Qe2, and Qxe5 (never overlook a check just because the needed square already

is occupied by the enemy). Consider whether any of those moves also attacks anything else and see that Qxe5+ aims the queen at the loose rook on a1. The only hitch is that the e5 bishop (the e5 square, really) is protected by a pawn. Black has nothing he can use to capture the pawn, so ask another question: if the bishop is taken by another piece and White recaptures with the pawn, will e5 become available?

draw the knight onto e6 so that the queen can capture it and execute the double attack at the same time. Is there any other piece the knight protects that could be taken? No. Well, when in doubt, play with other checks you can give and their consequences. Consider Rg5+. Notice that White’s queen greatly constrains the ability of the Black king to flee such an attack; indeed, the king cannot be moved at all. Black’s only option is Ng6, interposing his knight between the rook and king. With the knight thus budged from f8, the way is clear for White to play Qe6+ and win the bishop. It's hard to overstate the value of looking at checks and their consequences.

Dg116: Black to move Yes, it will. Black thus plays 1. …RxB+, 2. f4xR, Qxe5+, and then takes the rook, gaining a piece and a pawn. In the previous two positions we captured the guardian of the needed square; here we capture the occupant of the square and invite recapture. The result in either case is the loosening of the square.

Dg117: White to move Dg117: This one is harder. A scan for loose pieces turns up the bishop on e2. White’s queen can attack the bishop and check the Black king by moving to e6; but e6 is protected by the knight at f8. White can’t capture the knight, and there is no way for him to

Dg118: White to move Dg118: Search for loose Black pieces. Only the rook at a8 is unguarded—but there is an open diagonal leading to it, making it a promising target. To exploit the situation you need a way to attack the rook while also attacking something else. The queen is the classic tool for such a purpose, but here White's queen has no checks to give. So move to another question: what mating threats does White have? A simple way to search for mating threats is by looking for pieces that attack squares next to the enemy king; adding an attack by the queen against such a square often creates a mating threat that is as good as a check for purposes of creating a fork. Here White’s d3 bishop attacks h7, next to Black's king. White’s queen also can attack h7 by moving to e4 or h5; so the queen’s move to either square threatens Black with mate on the next move. Of these two moves the interesting one is Qe4, since it also attacks the loose rook. Naturally you first ask whether the needed

square is available and find it is not: e4 is guarded by Black’s knight.

2.2.5. Loosening the Target by Exchanging It.

The procedures for handling this sort of problem are well-known to us now. We start by asking whether the knight can be eliminated with an exchange, and it can; 1. BxN, BxB leaves e4 unprotected, after which 2. Qe4 wins the rook after Black spends a move fending off the mate threat.

The studies so far in this chapter all have involved spotting a double attack waiting to be executed—and perhaps then perfecting it by loosening the forking square to make it available for the queen. Now we move to another pattern: the target piece—that is, the piece you intend to capture—does not start out loose; you have to loosen it with an exchange. Or it has to be moved onto a square where it is loose and can be forked. The thought process typically starts with the observation that your queen can check the enemy king; then, seeing no loose pieces it can attack at the same time, you get to work to create one.

We will study this way of creating and using mate threats in more detail soon.

Dg119: White to move Dg119: The key to this position is that White has a check he can give with his queen by moving it to e5—and from there the queen also is lined up against a pair of Black pieces on the fifth rank. Obviously Qe5+ isn't yet feasible because Black’s rook protects the square, but the potential for a fork should attract your attention and cause you to focus on getting rid of the rook. There are standard tools available for the purpose. A first recourse is to capture the nettlesome piece, but White can't; a second is to take something the rook protects, but this, too, is impossible. There remains a third option, however: threaten the rook with something less valuable than itself so that it has to be moved rather than just protected. A pawn is best for such purposes, so White plays the simple g3g4. If the rook moves to safety, White has the queen fork Qe5+, winning a piece.

Dg120: White to move Dg120: We’ll start with a simple method. Look for checks your queen can give that also attack another enemy piece. If the piece is protected, ask whether you can capture it with one of your other men; perhaps when its replacement recaptures it will be left unprotected and will be a suitable target for a fork. Applying this approach to the position on the left, we find two queen checks to consider: Qe4 and Qf5. Ask whether you can attack anything else with those moves and you see that Qf5 threatens the Black bishop at d7. The bishop is an unsuitable target; it can hit back, and anyway it is protected. So ask whether White can take the bishop with another piece, forcing an exchange that will replace the bishop with a better target. He can: 1. RxB, NxR leaves a loose piece where there used to be a protected one. Now Qf5+ wins the knight, netting two minor pieces for a rook.

Another way to see this would be to start by examining captures you can make and their consequences. One capture for White to consider is RxB. You see that it provokes NxR. The critical step is to think about how the board would look after this exchange, asking what would then be possible. Note that the knight would be left loose and so would make a great target for a double attack. Might it be attacked with check? Yes, with Qf5+.

Dg122: White has one queen check: Qxg6. This also attacks the bishop on f5; but the bishop is protected, and can capture on g6 anyway. So the next question is whether White has any other pieces attacking the bishop that he might use to force an exchange which will leave g6 occupied by a more suitable target. The answer is 1. RxB, RxR. Now 2. Qxg6+ takes the rook left on f5 and so nets a piece and a pawn. (Black was required to use his rook to recapture, of course, because the g6 pawn was pinned.)

Dg121: White to move Dg121: What checks can White give with his queen? Diagonal moves won't work because the queen is on a dark square and the king is on a light one. But White does have a check—his only one on the board—in Qxf5. So now you ask whether the move also would attack anything else and notice that the queen would be pointed at the bishop on d7. The bishop isn't loose, but it's attacked once and protected once. Thus consider a preliminary exchange that might leave behind a loose piece: if White plays 1. RxB, RxR, the result is a loose Black rook on d7. Now Qxf5+ forks the rook and nets a piece and a pawn.

Dg123: White to move Dg123: What checks can White give with his queen? Four: Qa4, Qb5, Qe6, and Qxf7. Two of those—Qa4 and Qb5—also attack the black bishop. The bishop is protected, so naturally you look for an exchange that would leave a loose piece on a6. White can go after the bishop with his rook; after 1. RxB, RxR, White has a good loose target to pair with his check of the king. He plays Qb5+ and takes the rook, again netting a piece.

Dg124: White to move Dg122: White to move

Dg124: Here's a similar position. What checks can White give with his queen? One: Qa4. Does the move attack anything else? Yes, the

bishop on a6, but the target is protected— until White takes it with his rook, causing a recapture by Black’s knight: 1. RxB, NxR. Now Qa4+ safely takes the knight.

double attack—is guarded by both the queen and the b6 knight.

2.2.6. Loosening the Target by Disabling its Guards. Now let's consider other ways of loosening a piece that you hope to fork: capturing its guard or luring the guard away with an attack on something else it protects. Dg126: White to move

Dg125: White to move Dg125: White has two queen checks in the example to the left: Qa3 and Qb4. Both moves also attack the bishop on a5, but the bishop is guarded by the knight at c6. There are two natural ways to deal with this: capture the bishop with another piece, so that the knight recaptures and is then a good target (our previous theme); or take out the knight directly. White has nothing attacking the bishop, so an exchange of the sort considered in the previous section is not possible. But does White have anything attacking the guard? Yes: 1. BxN, d7xB leaves the Black bishop loose; Qa3+ then takes it.

But pick one of those problems and play with it. The rook can’t be exchanged for a loose target as in the previous section, but ask whether either of its guardians might be taken and with what consequences. Indeed White’s rook attacks the Black knight, so walk through the capture, recapture, and resulting position in your mind’s eye. If 1. RxN, then 1. … QxR—and now the rook at d7 is loose and the e8 square is left loose as well. White takes the rook with the queen fork Qe8+, winning a piece. Notice how a single capture and recapture can have a terrific impact on the board, here creating a double attack where none had seemed possible. It shows why looking at exchanges is another good place to start your interrogation of a position. Here, for example, you might have begun with a look not at Qe8+ but at RxN. The important point then is to follow up by imagining the board as it would look aftewards and re-asking routine questions: e.g., might a check then be combined with an attack on loose piece? P.S. The White king was inadvertently omitted from this one; until the diagram gets fixed, imagine it on h2!

Dg126: (Here is another of those occasional diagrams in need of a repair; until the fix is made, pardon the omission of the White king!) White has a queen check to explore in Qe8. It might prematurely be dismissed as impractical, since the Black queen guards e8 and the rook at d7—the possible target of the

Dg127: What checks can White give with his queen? Only Qg4. Having seen this, dig for some way to attack a loose Black piece at the same time.

can’t allow this. And since he is unable to move his king, he has no choice but to take out the pawn with Nxh6. White asks what would then be possible. Returning to first principles, he looks for any checks he would be able to give and any forks he might inflict in the process. This leads to Qf6+, winning the loose knight.

Dg127: White to move The cluster of pieces at c8, d7, and e7 looks promising, but as yet contains no suitable targets; so ask what the effects of an exchange would be. Look in particular for any trouble you can start that will leave a Black piece loose at the end of it. 1. RxR, QxR leaves the c8 rook unprotected, and thus makes it a good target that White can reach from g4. 2. Qg4+ wins the rook after Black moves his king.

Soon we will look more closely at uses of mating threats to create queen forks, but the basic principle is clear enough: a mate threat that doesn't at all work to create mate may work wonderfuly in other ways—viz., to create a loose piece. In this case the point of the mate threat created with h5-h6 had nothing to do with actually achieving mate. The point was to force Black to rearrange his pieces in a way that would lead to new tactical shots. Try thinking about mate threats in this way: as a means to an end other than mate.

2.2.7. Moving the Enemy King into Position.

Dg128: White to move Dg128: And now a last related idea. We have seen that a first principle of tactical play is the importance of inspecting checks you can give and your opponent's responses. A second and related principle is the importance of experimenting with any mating threats you can create—most typically by directing a second piece at a square next to the enemy king that you already attack once. Here is a simple example. White’s queen hovers near the Black king. The situation is tense because White’s knight is pinned, but White does have one obvious offensive possibility: h5-h6, where his pawn then is positioned to provide cover for Qg7# next move (it follows the formula: the pawn adds an attack against a square already attacked once by White's queen). Black

Now consider a scenario opposite to the one we have been studying: you see a loose enemy piece you can attack, but not the other ingredient of a classic queen fork: a check you can give at the same time. You need to make the king move someplace where it can be attacked simultaneously with the loose piece. The most natural way to do this is with a preliminary check from a different piece or perhaps from the queen itself. The check forces the king to move, and once it reaches its new square a fork may follow. Another way to move the king is by initiating an exchange, rather than a check, that draws the king onto a square where it can then be attacked—or pushed around some more. The practical point: if you need to move the king, ask what checks you have and what the king protects that you might be able to capture; if the answers to those questions help move the king but not far enough, then ask them again.

Dg129: Black to move

Dg130: White to move

Dg129: In this first example, White’s rook is loose; that is a starting point for analysis because it gives you a target to focus on. Ideally Black would like a move that attacks the rook and gives check at the same time. Presently it can't be done, so look for any checks that might force the White king into a position where it could be attacked along with the rook. It turns out that Black has just one such check to examine: Rd1. White is required to answer with Kh2. Now reassess the resulting board, again asking whether Black can attack the king and the loose rook at the same time. This time you find Qb8+, winning the rook.

Dg130: Black’s rook is loose, but there is no way for White’s queen to attack it and give check at the same time. So look at the checks White can give and consider their consequences. There are five such possibilities: Qa8, Qe8, Qh7, Qh4, and Qh1. A couple of them—Qa8 and Qh7—can be dismissed without any real thought. But then there are the others: (a) Qe8+ forces the king to h7; this almost works because it then allows Qe7+, attacking king and rook. But of course Black replies RxQ. (b) Qh4+ forces Kg8 but leaves White with no good follow-up; from h4 there is no way to attack king and rook simultaneously. (c) Qh1+ also forces Kg8. But this time White does then have a move that attacks king and rook at the same time: Qg1+, winning the rook.

The other route to the solution is to look first at Rd1. When your rook has a clear path to the enemy king's rank, it's natural to consider moving it there and to ask what the reply would be. Here you see that White's king escapes to h2. The crucial thing is to keep pressing then, asking what your next checks might be and whether any of them can be turned into forks. This position is a nice study either way you look at it because the idea of a fork does not particularly suggest itself at the outset; it is not a case where there are visual clues indicating that the fate of White's king and rook are linked. Producing a crushing, gamewinning fork in two moves thus might seem magical to the uninitiated. But the magic is the residue of method.

Dg131: White to move Dg131: Black’s bishop is loose, so White’s energies turn to ways it might be attacked while also giving check. It can't be done from the current position on the board; White’s only check with the queen, 1. Qc8, doesn’t attack the bishop. But it does push the king to h7—and then might a double attack be possible? Keep your eye on the loose bishop,

which you are working to capture; and examine every check that would be available after the king moves, looking for a double attack. 2. Qf5+ wins the bishop. Notice the importance of not rushing off to examine checks with other pieces, such as White’s knight, in order to help arrange a queen fork; sometimes the queen can do all the work by itself, as it does here. (With Black’s queen poised to give check, White wouldn’t want to go forward with this sequence without making sure his own king will be safe at the end of it; the fork will cause White's queen to be taken far away from its king and leave it out of position to supply defense. But White would have a decent reply to Black's Qg1, Qe1, or Qc1, so the coast is clear for the fork.)

Dg133: White to move Dg133: It all starts with seeing a loose piece. Here Black has left his rook loose, so it's a target and the focus of operations. White can attack it with his queen but can’t give check at the same time, and the check that is available to the queen—Qe8—won’t change that. Yet the fork seems so close: Qd3 attacks the rook and would attack the king if only it were on h7. Look for checks by other White pieces that might push the king around, and you find just one: Rb8+, which forces the reply Kh7. Qd3+ follows, of course, winning the rook.

Dg132: White to move Dg132: Our drill used to be looking for checks. Now it's looking for loose pieces. (In practice you want to do both, of course.) Here Black’s bishop is loose, so look for some way to attack it and give check. The queen can’t attack the bishop with any of its available checks: Qf8, Qh8, Qe3, and Qxg6. But examine the consequences of those moves and you find that Qh8+ forces Kg5. Remember the goal: to attack the loose bishop and give check. Would that be possible from the new position on the board? Indeed: Qe5+ then forks king and bishop and wins a piece. Ideally you want to see this in one visual motion. Imagine checking the king with your queen from h8, and see the king move to g5 in your mind’s eye; then see it aligned with the bishop, enabling you to play Qe5+.

Dg134: White to move Dg134: Are any of Black’s pieces loose? Yes, the rook. White’s queen can attack it from d4 (and also from d7, but that’s unsafe), but not while giving check, and the checks Qc2, Qd3, and Qh6 all lose the queen. So look for ways to draw the Black king into harm’s way by checking it with another piece. White’s rook has a check in RxB. If Black replies KxR, then reconsider White’s attack on the loose rook—still the target. Now Qd4+ has become a working fork that wins back a rook and leaves White up a piece.

nerable position, and find 1. BxB+, KxB. Now Qd4+ forks and wins the knight. Since White's move gives check, Black never has time to carry out the knight fork he had been threatening.

Dg135: White to move Dg135: Again Black has left a rook loose. White’s queen has no way to attack it and give check—yet; its two possible checks at a2 and d5 both are met by Black with QxQ. But look for other checks on the board and see that the White rook has two: Rd8 and Rxg7. Examine each of them. 1. Rd8+ goes nowhere decisive after 1. …RxR, 2. QxR+, Kf7. But now ask what the board looks like after the other possibility—1. Rxg7. Black replies KxR. With the king moved, reexamine the checks that would then be possible; see that Qd7+ has been turned into a working fork that wins the rook.

Dg136: White to move Dg136: White is unhappy to see that Black has hit him with a knight fork from e3. But since the fork doesn't include a check, White’s response isn't tightly forced. He can think about taking the offensive rather than attempting damage control. So ask one by one: are any of Black’s pieces loose? Yes: the knight at e3 that is inflicting the fork. This is the target. White’s queen can attack it, but not while giving check; the Black king is hidden behind the bishop at g7. So look for other checks that might force the king into a vul-

This problem illustrates the importance of not panicking when threatened with a knight fork. It also is a reminder of why knight forks against two non-kings often are so much less effective than knight forks that give check. Here White doesn’t have to move his king, and so has time to mount a fresh threat of his own.

Dg137: White to move Dg137: Look for loose Black pieces and you find both the bishop at b4 and the bishop at g4. White’s queen has no checks that can be paired with attacks on either bishop, so he looks to his other pieces to help. The goal is a check that will draw the king out where it can be attacked at the same time as one of the bishops. The natural check to try first is one using White’s bishop, since that also vacates c4 and makes it available for the queen. Hence 1. Bxf7+; and then if Black replies KxB, White has 2. Qc4+. This attacks the king and both Black bishops, winning one of them and gaining a pawn. Dg138: This position is almost the same as the previous one but with an additional exchange required at the beginning: 1. Rxf7, RxR; 2. BxR+, KxB; and now Qc4+. Study this example to see how the same basic thought process still leads to the solution: the loose Black bishops are the targets;

Dg138: White to move

Dg140: White to move

if White’s queen can move to c4 and give check, it will win a piece. Bxf7 is ineffective here because of the rook on f8, so you keep looking for more artillery you can bring to bear and find that the exchange Rxf7, RxR makes possible the bishop check and sacrifice that in turn leads to the queen fork.

Dg140: Black has a loose bishop at c6. White’s queen has one safe, plausible way to attack it: Qc2. If the Black king could be drawn onto g6, a fork of king and bishop would be possible. White’s bishop can help by taking the pawn at g6, giving check and taking a piece that only Black’s king protects. If Black replies KxB, the board is now arranged for a queen fork with Qc2+, gaining White a pawn.

2.2.8. Clearing the Path to the Forking Square.

Dg139: White to move Dg139: Are any of Black’s pieces loose? Yes, the rook at a8; so that's our target. White’s queen has two ways to attack it: Qe4 and Qf3. Neither move yet inflicts a check, but perhaps the Black king can be drawn into position to be forked on f7 or h7 with an initial check or capture by another of White’s pieces. White plays Rxf7. If Black replies KxR, then Qf3+ wins the a8 rook. This is a good example of using a capture rather than a check to attract the king onto a square where it can be attacked; White forces the king to move by taking something that only it protects.

Now we move to a slightly higher level of difficulty. These are positions where there is a square from which your queen might attack the enemy king and a loose piece, but where another piece or two blocks the way: blocking the queen’s path to the forking square, or its path from the forking square to one of the targets. Once you see such a situation, the methods for resolving it are straightforward enough; but often it can be hard to see in the first place. Our first pattern consists of cases where the queen's path to the forking square is blocked. You discover this situation by looking for the ingredients for a double attack and finding a square from which it can be made; then you consider whether the queen’s path to the square can be cleared with a threat or exchange.

Dg141: White to move

Dg142: White to move

Dg141: In the position, start by looking for the raw elements of a fork. Why, look: with Qa8, White can fork Black's king and his a7 pawn. How splendid! Yet perhaps we can do better. First, does Black have any loose pieces? Yes, the rook at d7. Ideally you want to check his king and attack the rook at the same time. Are there squares from which the queen could do that? Sure: e6 or e8 (in principle d5 and f7 would work, too, but the rook protects those so they aren't worth worrying about—and then there's c8, which is inaccessible). So if the Black bishop on e5 were out of the way, White would have a good double attack. Can the bishop be captured by something other than the queen? No, and anyway after any capture Black would recapture with a pawn on e5 and the White queen’s path still would be blocked. You want the e-file cleared, so instead try threatening the bishop with a pawn that it will have to flee. White thus plays f3-f4. If Black moves the bishop out of the way to d6, Qe8+ wins the rook. (In the alternative, of course, Black might choose just to forfeit the bishop; his best reply to f3f4 is Qh5, allowing him to reply to f4xB with f6xe5.)

Dg142: Again, start by looking for the ingredients of a double attack. Black has a loose rook at a8: a good target if you can take advantage of it. So ask whether you can check his king and attack the rook at the same time. Well, you can't; but are there any squares from which it could be done, whether or not they now are within reach? Yes: in principle c6 would work, though at present it's protected and the queen's path to it is blocked. Look to see what stands in the way; ask what methods you have for clearing the queen’s path through—and especially what exchanges. The natural answer is 1. RxN, d7xR, 2. Qxc6+, recapturing the rook and winning a piece and a pawn. Notice how the single blow (RxN) takes care of both of White's problems at once, getting his own rook out of the way and forcing Black to replace the protected occupant of c6 with a loose pawn.

The hard part here is seeing the potential for a fork in the first place, since at the outset your queen has no promising checks. The trick is to go with the clues that are available: see the loose piece, and realize there is a square from which you could give check—i.e., a forking square—on e8.

Dg143: Black to move Dg143: The drill repeats. Start by looking for the ingredients of a double attack and work backwards. Does White have any loose pieces? Yes, a bishop at b5 and knight at e5. The question is whether Black can check White's king and attack one of those targets at

the same time. The path from a5 to the king is clear, and from a5 the queen also could attack the bishop or knight (this is a classic pattern in the opening; we studied it earlier in the chapter). So you've found a forking square, and now the question is how to get the queen to a5. Black’s own pawn is in the way at c7. Try to clear it in a threatening manner that will require a response from White and give him no time to defend against the coming fork. The simple move c7-c6 attacks the bishop, forcing it to move; wherever it goes, Qa5+ then wins the loose knight.

Dg144: Black to move Dg144: Strictly speaking White doesn’t have any pieces that are loose, but his bishop at h6 is attacked once and protected only once, and by another White piece (the queen) rather than a pawn. In a sense that makes the bishop as good as a loose piece: if Black can attack the bishop and give check, the bishop will be lost; it will be attacked twice and protected just once, so BxB will result (White wouldn’t be able to recapture with QxB, because then Black would play QxQ). But all this assumes Black can get his queen onto a square where it can give check and attack the bishop at the same time—viz., h4. Black’s own knight at f6 stands in the way. The trick is to vacate the knight from the square in a way that forces a time-consuming response from White; so look for captures the knight can make. 1. …Nxe4 attacks White’s queen and can’t be ignored. White responds with 2. f3xN or 2. NxN, NxN; 3. f3xN. Either way, Qh4+ then wins the bishop and Black nets a pawn with the sequence.

Dg145: Black to move Dg145: The analysis here sounds almost the same as in the previous frame. Start by looking for the ingredients of a double attack and work backwards. If you ask whether White has any loose pieces, the answer again is “not quite" — but the b2 rook is attacked once and protected once, and by another White piece (the queen) rather than a pawn. This means the rook is underdefended; if Black can attack the rook and give check, the rook will be lost. But all this presupposes that Black can get his queen onto a square where it can check White's king and attack the b2 rook at the same time—i.e., d4. Only Black’s own knight already on d4 stands in the way. The trick is to vacate the square in a threatening way that requires a time-consuming response from White; so you look for captures and threats the knight can make. Nxf3+ forks White's king and rook and requires the reply g2xN. Qd4+ then wins the rook at b2 as described above. A general point to take away from this position and the previous one is that when you examine your opponent’s pieces, you want to note not just whether they’re protected but how they’re protected and whether they also are also under attack from other directions already. It's worth studying these two cases until it's clear that the targets (the rook on b2 here, and the bishop on h6 in the previous position) are vulnerable to forks in the same general way that loose enemy pieces would be.

Dg146: Black to move

Dg147: White to move

Dg146: First, does White have any loose pieces? Yes, the bishop at d3 (and also the rook at a1, but it’s inaccessible for now). You would like to check White’s king and attack the bishop at the same time, so look for a square from which the queen might do it. You see that e3 fits the bill, and that the queen could reach it directly if Black’s own pawn at e5 weren’t in the way. So ask whether the e5 pawn can vacate its square in a hostile manner that requires a time-consuming reply. Yes: 1. …e5xd4; 2. exd4 (or cxd4), Qe3+ wins the bishop. You likewise might have seen this by imagining the consequences of pawn trades available to you in the center. You see that the first round of captures just described leaves the queen with a clear path to a new check— and fork—at e3.

Dg147: White is behind in material and needs to make something happen. Step 1: Experiment with checks, including a brazen gesture such as Rd7, which invites Black to play BxR. Step 2: Consider the board as it would look afterwards; ask what lines would have been opened or closed as a result and what new checks you might then have. Here Black’s bishop would have evacuated the sixth rank, permitting White to play the check, and fork, Qf6+ (taking protection from the pawn on e5). The fork doesn’t quite work because Black’s rooks are connected and guard one another. So persist and ask what move Black would make in reply to Qf6+. His king would be forced to e8. Then Qxh8+ works for White after all; it's made safe because the connection between Black’s rooks has been broken by his king. More importantly, it’s a skewer that wins Black’s other rook: Black has to move his king back to the seventh rank, and now White has QxRa8— and a won game. Notice how goading Black’s bishop onto d7 removed d7 as a flight square for Black’s king—and thus forced Black to respond to 2. Qf6 with Ke8.

The likely payoff from seeing all this, of course, is the gain of just a pawn; for if your opponent sees the fork coming — and you should assume he will—he will not recapture after exd4. By the way, it also might have occurred to you to start with e5xf4 (instead of taking d4); this likewise moves Black's pawn out of the way. What's wrong with it? The trouble is that this time White can reply Nxf4, and then his knight suddenly protects the bishop on d3 that you had counted on as a target: it's no longer loose!

So you have a winning idea if Black responds to 1. Rd7 with BxR. But what if he doesn’t? Consider whether he has anything better. His only alternative would be to move his king to f8 or e8. Think about what your next check would look like either way. If he plays Kf8, you have QxRa8—mate. If he instead tries Ke8, 2. QxRa8+ no longer works because Black has KxR. That’s okay, though; instead you play 2. QxBe6+, forcing Kf8; then 3. Qf7#. So Black is required to play 1. …BxR in the first place to avoid mate. (These trains

of thought are worth reinforcing until they are clear.) Stepping back and looking at the original position, observe the open diagonals leading to Black’s rooks. See how they invite the idea of a queen fork, especially with the king on a center file and especially with a friendly pawn in the center poised to protect your queen. The basic forking possibility (Qf6) is a little elusive at first because the rook on h8 doesn't become loose, and thus doesn't become a good target, until later. You might think like this: if I could get my queen onto f6, it would fork Black's king and rook, and the rook would become loose if the king were forced by the check to step back onto the eighth rank. So if only I could get my queen over to f6...) The other lesson to take away is the value of considering bold moves like Rd7+. The move looks counterintuitive because it loses a rook on the spot and you already are behind in material. But this won’t stop you from experimenting with the move so long as you remember that the frequent purpose of such checks is just to force changes on the board that make forks or other tactics possible. That probably is the easiest way to see the solution here: not by spotting the forking idea from the outset, but by experimenting with checks you can give and then with new checks that become possible after your opponent's replies. This leads you to Rd7 as a first move and then Qf6—at which point the fork comes into view.

2.2.9. Clearing Paths to the Targets. Now consider another variation on our theme: a potential fork is frustrated by a piece lying between the forking square and one of the targets—the king or the loose piece. Again much of our attention will be devoted to the process of noticing such situations; once they are found, standard tools—threats and exchanges—often can be used to resolve them.

The most important general skill here is the ability to see “jump checks”: moves that would give check if some piece (perhaps an enemy piece, or perhaps one of your own) weren’t in the way. These are important to see generally, and they are especially important if you have found a loose enemy piece. For then you turn all your efforts to looking for a way to attack the loose piece and give check at the same time, and you don’t want to overlook a check just because there is a piece that would need to be gotten out of the way before it can work. The best way to find checks like this is to try just aiming pieces at the enemy king. If pieces of your own are in the way, look for time-consuming threats you can make by moving them. If your opponent’s pieces are in the way, try to force them off their squares with threats or by taking pieces they protect.

Dg148: White to move Dg148: In this first example, look first for any loose enemy pieces. Here Black’s rook is loose at d7. Can White’s queen attack it and give check at the same time? No, not yet. But if the queen moved to g4 it would be aimed at both king and rook; thus only the Black pawn at g7 prevents a successful fork. So ask whether White can draw that pawn out of the way by taking something it protects. The g7 pawn guards the bishop at f6, which White can take with his rook. So 1. RxB, g7xR; 2. Qg4+ gets the Black rook and wins a piece. Dg149: Almost the same. This time it is Black's turn to move, so first look for any loose White pieces and find the rook at a2. Now ask whether Black’s queen can attack it and give check at the same time.

check the king and attack a loose piece elsewhere at the same time.

Dg149: Black to move No, not yet; but if the queen moved to d5 is would be aimed at both king and rook. Only the White pawn at g2 prevents this from being a successful fork. So ask whether that pawn can be drawn out of the way by capturing something it protects. It protects the knight at h3, which Black can take with his rook. So 1. . . . RxN; 2. g2xR, Qd5+ wins a piece.

Dg151: Black to move Dg151: A search for checks for Black turns up Qb1; a search for loose White pieces turns up the bishop on b7. Qb1+ would indeed be a winning queen fork if the pawn on b3 weren’t in the way. So now the position becomes easy: to move a pawn, take something it protects. Black plays RxN; White replies b3xR; and Black then has Qb1+, taking the bishop next move and netting two pieces for a rook. Anytime you have long open lines available to your queen, inspect them carefully for opportunities like this.

Dg150: White to move Dg150: Are any Black pieces loose? Yes, the knight at d7. Can White’s queen attack it and deliver check at the same time? No, but Qg4 would aim the queen at both a loose piece and the king; it would be a winning fork but for the pawn at g7. White’s goal therefore is to draw that pawn out of the way. Ask whether the pawn is protecting anything that White can attack, and you are led to 1. Bxh6; now if 1. ...g7xB, then 2. Qg4+ takes the knight, gaining a pawn and wrecking the Black king’s pawn cover. These first three examples all are basically the same, of course; they involve creating holes in the king’s pawn cover so that the queen can

Dg152: Black to move Dg152: It might look for all the world like Black has nothing here; the lines to White’s king appear cluttered and inaccessible. The trick is to notice that White’s rook on a1 is loose, and then that Black’s queen is one move from being able to attack it with Qg7. (The open long diagonal should be conspicuous.) The question is whether the attack on the rook can be paired with a check to create a fork. A line from g7 to White’s king would

need to be opened, so study the obstacles on that line—the little cluster of White bishop and Black pawn, with a White pawn on f5. This cries out for a pawn capture that clears both blockages out of the way: g6xf5—and now White has to either move the bishop or lose it. If he moves it, Black has Qg7+, winning the rook. At first the g-file in this position looks impassible because of the two men that lie on it; Black’s pawn capture is a very useful maneuver, worth a long look, as it creates an unexpected open line in a hurry. Notice that this position is structurally similar to the previous one. In each, you start by seeing that your queen is one move from being able to attack either the enemy king or a loose enemy piece (half a fork); and you see that the queen also would be aimed at the other half of the fork—whichever of those two pieces (the king or the loose piece) it wouldn’t be attacking directly. The hindrance in both positions was that one of the lines the queen needed was blocked; the challenge both times was to get rid of the blockader; the solution in each case was to start with a capture of something the blockader guards, forcing it to evacuate the needed line and leave it open. Dg153: Black’s queen has a check that must be seen (queen checks always must at least be seen!): Qb4. When you examine a queen check you are looking in part for forking ideas; the question is whether Qb4 attacks anything else.

Not directly, no, but from b4 the queen is aimed at the knight on h4, which is loose and therefore a target. The problem is the White pawn on f4. Can it be eliminated? Best would be to take something the f4 pawn protects, but that’s not going to work here; in reply to Nxe5, White has QxN+. So toy with more direct threats to see what they do. Thus g6-g5 is natural to consider, and then you see that it does more than threaten the White pawn. It attacks the knight, too, which has no safe place to flee—an occupational hazard of a knight placed on the edge of the board. So White is about to lose the knight unless he takes the Black pawn that threatens it; yet if he plays f4xg5 he loses the knight anyway to Black’s queen fork Qb4+. (White also can reply to Black’s initial pawn push with Qd4, preparing Qxa4. Or White can play 2. Nxf5, QxN. The material outcome is the same.) There is a matter of move order to consider. Black could start with Qb4+, forcing Kc1. Then comes g6-g5, and again White must lose the knight (in effect White’s f-pawn is now pinned). Why not do it this way? Well, you could. But now if White plays 2. Nxf5, Black can’t recapture with his queen, for it is over on b4. Instead Black has to recapture with his e6 pawn, which in turn gives White a passed pawn on e5 that he can push to e6, threatening to promote it eventually and menacing Black’s knight right away. Black can deal with this (one possibility is Qe7, pinning the pawn; another is Qc5, attacking White’s queen), but starting with g6-g5 avoids these complications.

Dg153: Black to move Dg154: White to move

Dg154: Black has a loose rook at d7: a target. White’s queen can attack it by moving to h3, g4, or f5 (you attack rooks diagonally, and bishops horizontally or vertically), but none of these moves attacks anything else at the same time; the path to the king is blocked by the pawns in front of it. So consider what other resources White can bring to bear— what forcing moves, and with what results. Experiment with the knight. It has an easy fork with the check Nf6+; Black has to reply g7xN, not only to avoid losing the rook but to avoid being mated with Qxh7. But then a line to the king has been opened; now Qg4+ attacks both king and rook, winning the exchange.

If you need to move an enemy pawn, whether in front of its king or elsewhere, the most common method is to take something it protects. But another technique to remember, shown here, is to imagine sticking one of your pieces en prise to the pawn and consider whether it makes an interesting threat that your opponent would feel obliged to extinguish, thus leaving you with an open line on which to play a tactic. Or maybe he will decide that he can't afford to extinguish the threat by making a capture because its side effects are too severe (i.e., the queen fork)— so instead he has to let you push your first threat forward.

Dg155: White to move Dg155: This is similar to the previous frame. What Black pieces are loose? The knight at a5 and the rook at e2. It would be hard to fashion a double attack against the knight, but the

rook, isolated deep in White’s territory and near the White queen, is a perfect target. Is there a square White’s queen can reach that would enable it to attack Black’s king and rook at the same time? If the queen were on g4 it would be aimed at both targets. But its path to the king would be blocked by the pawn at g7, and of course the White knight already occupies g4. What White needs is a way for the knight to vacate g4 with a capture or threat that requires Black to respond, and a way to remove the pawn at g7. Nxf6 and Nh6 suggest themselves as ways to achieve both objectives at once. Nxf6 doesn’t quite do it because Black can reply QxN without moving the g7 pawn. But Nh6+ forks queen and king and so requires g7xN in response—after which Qg4+ forks and takes the Black rook.

Dg156: White to move Dg156: This position illustrates a very useful principle. White has a queen aimed at h7. If the queen had cover from another White piece aimed at the same square, the result would be a mating threat. A classic way to so aim a second piece is by putting a bishop behind the queen, as with 1. Bd3. There is then a standard way for Black to address such a threat: he moves his g-pawn forward to g6, interrupting the queen’s path (and, in this case, threatening it to boot). But the point of the mate threat wasn’t to mate. It was to force this disruption of the pawn cover in front of Black’s king. When pawns step forward as Black’s gpawn does here, lines to the king often are opened that can then be used for other tactical purposes—such as forks. In this case notice that Black has a loose bishop on d6; after the little sequence just sketched White takes the

bishop with 2. Qf6+, Rg7 (interposing to block the check); 3. QxB. The pattern here is important to master: lining up pieces against the enemy king’s position so he is forced to move his pawns forward, then exploiting the line he has opened with a fork or other tactic.

Dg157: White to move Dg157: See the loose rook on c8. See the exposed enemy king on h8. See that in one move your own queen nearly can get into position to attack both targets with Qh4. Neither part of the attack works yet; the point is just to recognize this as a common general pattern for a queen fork: the check against the exposed king down the side of the board, more or less, and the accompanying diagonal attack against a loose piece on the back rank. The question is whether it can be made effective. The pawn on h5 blocks the queen’s path on the h-file; and the fork would have to be executed from g4 anyway in order to reach the loose rook (or else the rook would have to be moved). Well, getting the pawn out of the way is no great challenge; just take what it protects with 1. RxN. After h5xR, White can work with checks and thus is in the driver’s seat: 2. Qh4+, forcing Black’s king to the gfile; then 3. Qxg4+ (the fork) and 4. QxR. So White gets a pawn, a knight, a rook for a rook—if Black bites by recapturing after White starts with RxN. He probably won’t, which is fine; it leaves you with a piece. But you also have to make sure that he doesn’t have any killer threats of his own to play instead, and at this point the position becomes more demanding than at first appears. Look at

any checks Black can play—and not just the first check he can give, but strings of checks. You need to satisfy yourself that you can escape whatever mess he can create. Imagine him replying to RxN with Qa2+. This forces your king to c2; then comes Black’s next check, b4-b3+. This time your king escapes to d1, and Black is out of checks. He can play Qxb2, but since that’s not a check it leaves you with a move to take your rook on g4 out of the danger it still faces from the pawn on h5. That last point is important. The purpose of looking at Black’s counterthreats is partly to make sure you aren’t leaving yourself open to a mating trap, but it’s also to make sure that Black can’t play any forcing moves (checks, mate threats, or captures) that will force you to move your queen; for remember that while all this action is going on in the near left corner of the board, your rook still has been left en prise to Black’s pawn on h5. The only thing preventing your rook from being taken is the threat of the queen fork discussed in the first paragraph. If Black can find a way to distract your queen, your rook will be a goner because Black will be able to take it without consequence. But he can’t. There is yet one more possibility you would need to consider: Black can reply to Rxg4 with b4-b3. Again, you are looking for major counterthreats Black could launch; this counts as one of them because once the pawn has moved to b3 it is ready to support mate by the queen on a2. The pawn move also uncovers the threat of QxQ next move. Black might be thinking that this will force White to make the preemptive strike 2. QxQ; then after Black replies RxQ, the queens have been traded and Black is ready to launch a mate threat of his own with Rc8-a8, preparing Ra1#. But this needn’t scare you, for White has another move to play in the middle of that sequence. If 2. QxQ, RxQ, then White goes with 3. Rc1h1. This pins the pawn on h5, so now White’s rook at g4 is safe; more to the point, with rooks on both the g and h-files White suddenly is ready to mate with Rxh5. Indeed, Black cannot escape that result.

This position is worth a good look as a study in anticipating your opponent's counterplay. The reason the issue needs such close consideration here is that White's king is so exposed. It's next to an open file on which Black has a queen and rook, and its only flight square (c2) is perilously close to being sealed off by Black's b-pawn. This means that White has to be very careful not to end up mated or otherwise burned by operations against his king's position. It can happen at any time—even in the middle of a tactical sequence White initiates elsewhere on the board.

loose piece on the fourth or fifth rank: the queen at least would be aimed at both pieces, with its path to the king blocked by the knight at c6 and its path to the loose knight at e4 blocked by its own pawn at d4. So White looks for ways to get rid of those blockages, preferably at the same time. He starts by moving the obstruction he can control (his own d4 pawn), and using it to threaten the obstruction controlled by the enemy. Thus d4-d5 attacks the knight and forces it to move out of the way. Now Qa4+ wins the knight at e4.

2.2.10. More Complicated Cases. Now let's try some cases where there is more than one complication to address. Here we will start to see some problems where none of the ingredients of a fork is obviously in place at the beginning. This makes spotting the potential for a double attack harder. Instead of looking for obvious tip-offs like loose pieces the queen can attack or available checks, we have to use a little more imagination; we look for familiar visual patterns and we examine checks, captures, and threats, searching for signs that a fork is coming into view.

Dg158: White to move Dg158: In the position pictured here, ask whether Black has any loose pieces; you thus are led to the knight at e4. White can’t attack it and give check at the same time; indeed, White has no checks at all. But if White’s queen moved to a4 it would be close to executing the classic pattern seen at the beginning of the chapter, attacking the king and a

Dg159: Black to move Dg159: White has a loose bishop at a4 (and also two loose rooks which are less accessible). Is there a square from which Black's queen would be aimed at both the bishop and White's king? Hmm: h4 is an interesting start, as from there the queen could give check and would win the bishop if the e4 pawn weren’t in the way—always assuming Black's queen could get to h4 past the knight at f6. So Black begins playing with ways to move both the knight and the e4 pawn out of the way. The natural method is to use the knight to attack something the e4 pawn protects—like the d5 pawn. 1. … Nxd5; and then if White replies e4xN, 2. ...Qh4+ wins the bishop. You might just as well have seen this by playing with any captures you can make and asking what would be possible on the board as it would look afterwards. This leads you to Nxd5; after imagining the recapture e4xN, you look for any new checks you would be able to give and see the fork Qh4+.

after that exchange, and re-ask the important questions: what checks now would be available, and what loose pieces? There are two checks: Qd3 and Qc2. The interesting one is Qd3, because it also attacks the Black bishop on d5. The bishop is protected once, by Black’s queen. But notice that now it would be attacked twice, by the White queen and rook. So Qd3+ wins the bishop after Black’s king retreats. Dg160: Black to move Dg160: White has no loose pieces and Black’s queen has no checks. But we examine the consequences of every check as a matter of course, and here Black has two of them: NxB and Nf3. Nf3+ leads nowhere; White plays g2xN. But what happens after NxB+? White has to play QxN to recover his piece. That little exchange would mean a significant change in the position: Black’s knight and White’s bishop both would be gone, and White’s queen would be moved to e2. So rethink what would then be possible, noting any lines that would have been opened, any checks they would make possible, and any White pieces that would have been left loose. Black would be able to deliver a check with Qd4, and at the same time attack White’s newly loosened knight at c3: a perfect double attack, winning a piece.

Dg161: White to move Dg161: White has no queen checks and Black has no loose pieces (except his queen, which generally is not a suitable target for a queen fork). Again, though, it is our practice to examine every check of any sort, and here White has one: BxN, which leads to KxB. All right; now examine the board as it would look

Dg162: White to move Dg162: Here is a more challenging one. Black has no loose pieces except his rooks, which are tucked out of danger, and White has no checks to give. The most likely way to see the chance for a double attack here is to experiment with captures and their consequences. There is just one possible capture here for White: Nxd5, which more or less requires Black to play c6xN. Then how would the board look? What checks would then be available? Answer: Qb5, which would attack the bishop at b4 as well as the king. The bishop is protected by Black's queen. But it also would already be attacked once by the White bishop at d2 (remember that when you think of Nxd5, you imagine the knight gone from its current square and see the open lines that result). So the Black bishop would be as good as loose: after Black moves his king in response to Qb5+, White plays BxB and Black dares not recapture. The tricky part of this example is seeing the potential for a double attack at all, since none of the ingredients are visible at the start. But even from the beginning you might notice a basic pattern that is familiar by now: by moving to b5 the queen would be aimed at the

enemy king and would have Black’s bishop just underneath it. Double attacks by the queen often look like that. It doesn’t quite work yet because the pawn at c6 blocks the check and protects the needed square, and because the bishop is protected once and not yet attacked at all. Still, if you can see the rough outlines of the familiar pattern, you can then play with various forcing moves on the board, like Nxd5, with a view to making the queen fork effective.

here, but the geometry of Black’s position should be provocative: QxR aims the queen at Black’s king and also attacks the bishop at a5, which would then (i.e., with the rook captured) be left loose. So see if you can move your knight away from e6 with a threat. The first type of threat to consider is a check. Ng5+ is no good, as it gives Black a way to both extinguish the check, save the rook, and guard the targeted piece (the bishop on a5) in one stroke: RxN.

You also might see the tactical idea here by first observing that Nxd5 is a knight fork of Black’s queen and bishop. Since the Black bishop would also then be attacked once by White’s bishop, the knight fork is a real threat to Black and must be met with c6xN. This then becomes a problem similar to the knight forks we already studied where you imagine playing the attack knowing that it will fail when your knight gets taken; you ask what would then be possible, and particularly what checks you would have available. Here that inspection would turn up a check by the queen which also attacks the bishop for the second time.

So now consider your other knight check: 1. Nd8+, in reply to which Black has to either take the knight with his queen or else move his king. If he plays 1. …QxN, White has 2. QxR, forking Black’s king and bishop and winning a rook with the sequence. If Black instead moves his king to f8 or g8 in reply to the knight check, the results for him are even worse. If the king goes to g8, it still gets checked by QxR and mate follows soon for White; if Black moves his king instead to f8, then after QxR White can hold off on QxB and instead move his own rook over to the hfile and prepare to drop it to h8, creating havoc there (likely in the form of a skewer).

Dg163: White to move Dg163: Here is another trickier position. Black has two loose pieces: the rook and the knight. The knight is out of reach, but what about the rook? It almost seems that it could be taken for free by the queen right now; then Black plays QxN, attacking White’s queen, and White has the exchange to show for his trouble. But remain calm and see if you can find something that is better still; don't assume the first good move you find is the best one possible. The queen has no good checks

For now, though, it is enough to have seen the power of the initial move Nd8. The challenge of this problem, a bit like the challenge of the previous one, is that White ends up taking a piece that was not loose at the start by inflicting a check that also was not available at the start. There are various ways you might have spotted the idea: by recognizing the relationship between Black’s bishop and king, which looks like a lot of other double attacks we have seen; or by examining every check from the outset (standard practice), finding Nd8+, and seeing that afterwards QxR wins the bishop; or by seeing that even if the bishop at a5 is not loose, it would become loose as soon as White played QxR with only the white knight standing in the way of a good fork. You look for ways the knight can evacuate its square with check, and there you have it. Dg164: Again we begin with no possible checks for White and no loose Black pieces (except the queen, which makes a bad target,

and bishop, against which nothing is possible).

more exposed to brutal tactical shots. It shows how vulnerable a position can be when pieces are protected by other pieces (rather than pawns). A series of captures can force the pieces all over the board and rather abruptly leave one or two of them loose.

2.2.11. Using Mate Threats.

Dg164: White to move Still, we do have some familiar geometry: Qd5 aims the queen at both the Black king and the rook at a8. Neither side of the attack yet works, but the basic pattern is something to keep in mind. The next step is to experiment with checks (White has none) and with captures. The obvious spot for an exchange is f5, where Black has a knight that White attacks. How many times is it attacked, and how many times protected? Twice and twice. So White imagines 1. NxN, BxN; 2. BxB, RxB. Here is the key moment in the exercise: imagine the board after those exchanges, and re-ask what checks and loose pieces are available. Now Qd5 looks quite different. It’s a check (the only one White then has), and the rook at a8 would be loose and so would be lost to the double attack. This problem is a good illustration of two things: how much a couple of exchanges that don’t seem to do much by themselves can change the board, and the importance of asking simple questions about how the board will look after such exchanges are complete.

Take the opportunity of this position to think, too, about the coordination of Black’s pieces—and White’s disruption of it. In the diagram Black’s pieces protect each other nicely: his rooks guard each other, and his bishop guards both knights and prevents White from giving check on d5. With a couple of exchanges White ruins this coordination, suddenly leaving Black’s position much

Often the queen can attack a loose piece while at the same time not checking the enemy king but threatening mate. The enemy has to address the mating threat, so the loose piece is lost just as it would be if the queen had delivered a check. To master this pattern it is important to understand a couple of principles about mating threats and how to spot them. It usually takes two pieces to create a mating threat (or mate itself, of course). The threat of a back rank mate is a prominent exception, but for now just think about a classic set of cases that does follow the pattern: your queen is poised to attack a square next to the enemy king that already is attacked by one of your other pieces. At the same time your queen attacks a loose piece. Your opponent has to defuse the mate threat just as he would a check, giving you a move to take down the target.

Dg165:White to move Dg165: The diagram illustrates the idea in skeletal form. White has a bishop trained on g7. His queen can threaten mate by jumping to d4 or g4 because either move creates the possibility of Qxg7#. Those mate threats will make a fine anchor for a queen fork of any loose pieces Black leaves within range of d4

or g4. The White X’s in the diagram thus indicate squares that White indirectly controls because of the possible fork. (He already controls d7 with his queen; but imagine a pawn on d2 and the control again becomes indirect.) If Black leaves a loose piece on any of them (or even a piece defended once but also attacked once by another White piece), White may be able to win it by playing one of his two mate threats, Qd4 or Qg4. Black will have to respond to the mate threat by stepping forward one of the pawns in front of his king or in some other way, and then White will win the target. In addition to taking Black pieces left unguarded on those squares, White also can carry out other operations there (exchanges, or putting his own pieces onto the squares) with more confidence than might appear to the untrained eye. In real play the details of what White can do here naturally will depend on which piece Black has left on those vulnerable squares, and of course on other pieces on the board that will complicate the picture. The e6 square is defended by a pawn; White wouldn’t be able to use his queen to attack a bishop on a diagonal; etc. Or suppose Black has a loose bishop on b4 and White forks it with Qd4 or Qg4. Black can save his piece by playing the bishop back to f8; this both removes it from danger and adds a defender to g7, thus defusing the mate threat. But these are details. The important thing for now is just to realize that in this humble-looking formation White has a strong forking threat waiting to be unleashed, that it isn't related to any check he can give, and that it gives him a measure of control over many squares that appear not to be under attack. Dg166: Inspect the position for loose pieces and you find the Black knight on c6. White has no safe way to check the king and attack the knight at the same time (Qe8 would do it, of course, but Black’s queen guards the square). So next White looks for a way to attack the knight while threatening mate. Look for another White piece trained on a square near the king. Here we have a classic example that we will see several times in this

section: White’s bishop is attacking a square next to the Black king (h7).

Dg166: White to move If White’s queen moves in front of the bishop on the same diagonal―i.e., to g6―then White threatens mate on the next move: Qh7#. So Black will have to address the threat created by Qg6 by moving his king or bringing over his queen. Meanwhile Qg6 also attacks the loose knight. So after Black makes one of the replies just described, White plays QxN and takes the knight for free. Think of this as a double attack on the knight and on the h7 square.

Dg167: White to move Dg167: Here is the same principle in slightly different form. What Black pieces are loose? The knight at a7 and bishop on d7. White can’t give check and attack either piece at the same time, so he asks whether he might attack one of them while creating a mate threat. He looks for pieces he has trained on squares next to the king and sees that the bishop at a1 is aimed at h8. If White’s queen were to land on h8 the game would be over. So White just needs a square from which his queen can (a)

attack one of Black's loose pieces, and (b) attack the h8 square. Qd4, winning the knight, is the answer.

the same diagonal as the bishop—for example, by playing Qd4. But that doesn’t attack the rook, and anyway d4 is protected by White’s queen.

Dg168: White to move Dg169: Black to move Dg168: By now this one should be easy. Begin with the usual reconnaissance of enemy pieces, looking for any that are unguarded or underdefended; here it turns up the Black knight on e3. White can’t give check and attack the knight at the same time, so he looks for the makings of a mate threat: another piece that attacks a square next to the king. Once more his bishop answers the purpose; it attacks g7. So he looks for ways his queen might attack g7—the mating square—and the loose Black knight. He finds Qd4, which wins the piece. As these first examples all show, a bishop aimed at squares next to the enemy king can be a valuable resource, as it creates a fertile climate for double attacks with the queen. The mating threats it supports may be simple to defuse (here the simple pawn move f6 puts out the fire for Black), but of course the purpose of the exercise never was to deliver mate. It was to take loose enemy material. Dg169: What White pieces are loose? The rook at e1 (as well as the queen, but focus on the rook for the usual reasons). Black has no safe way to check the White king and attack the rook at the same time, so he looks for a mating threat. Here as before the bishop is the answer: it attacks the b2 square (and pawn) adjacent to the king. Black would mate if his queen were to land on that square. If you followed the pattern of the previous problems, you might look for a way to put the queen on

So Black looks for other squares his queen could reach that would allow it to attack b2. He finds Qb4, which threatens mate by Qxb2 and also threatens, and wins, the loose rook at e1. The point: there is more than one way for the queen to attack a mating square already being hit by a bishop.

Dg170: White to move Dg170: What Black pieces are loose? All of them. White has no way to check the Black king and attack any of those pieces at the same time, so he looks for a mating threat; he asks what other pieces he has attacking squares near the king. This time his bishop isn't helpful, but his knight is: it attacks g7. If White’s queen were to land on that square, it would be mate. So White looks to move his queen to a square that would allow it to attack g7 and also attack one of the loose Black pieces. This leads to Qg5, which wins the

rook after Black makes a move to protect against Qxg7#.

Dg171: White to move Dg171: The only loose Black piece is the bishop at a1. White can’t attack it and give check at the same time, so he looks for mating threats. His knight attacks f7 and h7; the attack on f7 is not powerful because Black protects the square with his rook as well as his king, but h7 is only protected by Black’s king. It follows that if White’s queen attacks h7 it will threaten mate; the h7 square thus can be treated a target in the same way a loose piece or the king itself would be. So the question for White is whether his queen can attack the Black bishop and the h7 square at the same time. It can; Qh1 threatens mate and so wins the bishop. The long backward move of the queen here is counterintuitive, and illustrates the importance of methodically looking at every way the queen can attack the vulnerable points in the enemy position.

it in the usual way: look for loose enemy pieces, checks, and mate threats. Black’s rook is loose; follow this observation by looking for a line the queen could use to attack it while also being aimed at the king. Qh4 suggests itself. The move seems to fail because the h6 pawn blocks your queen’s path to the Black king’s position. But there is more than one way for a fork to “work”; if the move doesn’t give check, it still is enough if it threatens mate. Examine the Black king’s position and you see that White’s rook on the open g-file has the king trapped on the side of the board, and you see as well that the king has no defenders. The conclusion: Qxh6 would be mate. So after White’s 1. Qh4, Black doesn't dare move his rook; he has to let it go. (Then again, no matter what Black does, White can force mate soon enough anyway. If Black plays 1. ...Kh7, for example, then White plays QxR and can't be stopped from playing Qg8#; Black can only delay the move with useless gestures like Ne8 or Qxb3+.)

Dg173: White to move

Dg172:White to move Dg172: White’s best move obviously is the free QxN. Or is it? This is a sterling example of the importance of looking beyond a good move to make sure there isn’t a better one. Do

Dg173: Black just played Bc5, adding a second attacker against f2 along with his knight; maybe he meant to threaten a knight fork there. To see why this was a mistake, look at the board from White’s standpoint and ask some standard questions: What mating threat can White make? His bishop attacks f7, a square next to the king and unprotected by any piece other than the king; so White asks whether his queen can add to the pressure against that square and attack any loose Black pieces at the same time. The answers are yes and yes: if White plays Qd5, he now has a mating threat; and he also attacks the loose

Black knight at e4. The knight can jump out of the way and help guard f7 with Ng5, but it's no escape. White already has g5 under attack twice. So after 1. Qd5 Black is obliged to lose material. He can play the check Bxf2+, so that his bishop takes a pawn with it on the way down; but then White calmly plays Ke2, and now two of Black's pieces are under attack—his e4 knight by White’s queen, and his bishop by White’s king. He will lose the knight next move. Lesson: leaving loose pieces around is dangerous business. Before putting his bishop on c5, Black should have noticed (a) that he already had a loose piece in the middle of the board, which always is cause for concern; and (b) that White had a bishop attacking f7, which is cause for additional concern since it sets up a mating threat if White can aim his queen at the square as well. Black would have been better off making a move to address one of those threats. Best is d7-d6, since then after 1. Qd5, Be6; 2. QxN, d6-d5 Black wins back his piece with a pawn fork. (We will look at pawn forks more closely in the later chapter dedicated to them.)

what lines would then be open, and with what tactical opportunities then available to you or your opponent. One warning sign is that at the end of the sequence White’s knight on e5, while not attacked, would be loose. Another is that Black’s bishop already attacks f2, adjacent to White’s king. Nothing except the king protects that square (a common state of affairs in the opening; this is why f2 and f7 often are considered defensive weak spots early in a game); so if Black’s queen were able to attack f2 as well, White suddenly would be confronted with a mating threat. The threat could be averted with various moves, but they would take time, and meanwhile Black would be able to take any loose piece his queen also attacked. None of this looks like an immediate worry in the position diagrammed here, but after the exchange of pawns and the recapture Nxe5 by White, the stage would be set for Qd4, threatening mate at f2 and attacking, and winning, the then-loose knight on e5.

Dg175: Black to move

Dg174: White to move Dg174: Let’s continue to look at the same idea from a defensive standpoint. Here White sees that Black’s pawn on e5 is defended once (by the pawn on d6) and attacked twice (by the pawn on f4 and the knight on f3). So he is tempted to play 1. f4xe5; then if 1. …d6xe5, 2. Nxe5. But please don’t play an exchange like this until you have imagined what the board would look like afterwards—including

Dg175: Here's yet another example of how the prospect of queen forks can figure into defensive thinking. The two sides are fighting for control of the center and especially of the e4 square. Black sees that the White pawn there is protected twice but that he attacks it three times. In his mind’s eye he plays 1. …Nxe4, 2. BxN, RxB; 3. RxR, QxR. But before executing this sequence he must ask the sorts of questions we have been discussing. First, would this liquidation of the position leave any open lines at the end that would allow the enemy queen to attack the Black king? Here Qg5 would be available to White, and from there the queen would join the f5 knight in attacking g7—threatening mate.

Indeed, that move already is available. What prevents it from working is the absence of a second target: the queen would be aimed at the rook on d8, but its path would be blocked and the rook would be guarded. But after the exchanges Black imagines on e5, these obstacles would be gone. Indeed, the resulting position would be one you saw about five frames ago: it leaves a fork for White. So the sequence Black imagines must not be played; after it is complete it results in 4. Qg5, Kf8; 5. QxR+, Qe8; 6. QxN. This example shows how a few precautionary questions, asked as a matter of course before entering into a series of exchanges, can save a lot of trouble at the end. You carefully imagine how the board would look after the series, including any new open lines and loose pieces; and you then ask the same questions about that resulting position that you ask about positions in front of you: would either side have any loose pieces that could be attacked while giving check or threatening mate? If this seems like a demanding position, note again that the mate threat Qg5 is available to White from the beginning. Both sides should be conscious of this. It means that if White’s queen were able to attack anything loose from g5 he would have a working fork, so any sequences Black attempts have to be inspected to make sure they don’t produce that outcome. The moral: if your opponent is a move away from being able to create a mate threat, no matter how ineffectual, keep a careful eye on it as the potential basis of a fork.

Dg176: White to move Dg176: Where is the idea this time? You have a bishop trained on g7. One important effect

of such a resource is that you can create a mate threat by adding an attack by the queen against the same square, as with Qg3; so the key question is whether you can make another threat with that move at the same time. You see that from g3 your queen would be aimed at the rook on b8. The position thus has the makings of a classic queen fork, but there are a few problems in the way of its execution. The rook is guarded by the knight on d7; the queen's path to the rook would be blocked by White's own rook on f4; and the forking square (g3) is guarded by the knight on e4. Yet none of these difficulties need detain you for long. 1. BxNd7, RxB is a simple exchange that leaves the Black rook loose; 2. RxN, QxR loosens the forking square and opens the needed line; 3. Qg3 calls for Black to reply Bf8 to stop the mate threat; and then 4. QxR nets a piece. (4. …Qxg2 gets back a pawn for Black.) Now consider a few “why not” questions: (a) Why not start with RxNe4 rather than BxNd7? The answer is that 1. RxN allows Black to recapture QxR and get his queen onto e4—a powerful posting—too early in the sequence. For then when you play 2. BxN, Black doesn’t recapture RxB; he plays Qxg2. Now the forking square you want no longer is available (Black’s queen guards it). You have won two minor pieces for a rook and a pawn, and if you aren’t careful Black is about to take another pawn with Rxe3. (Qxh3 also is available to him.) You can win back a pawn with 3. Rxd5, QxR; 4. Qg3 (at last you get to play the queen fork after all), f7-f6; 5. QxR+. But the overall sequence isn’t what you had in mind. Better to start capturing in the back of Black’s board with BxN, and save the invitation to Black’s queen until you’re ready to take strong hold of the initiative next move with a mate threat. (b) That explanation also shows why, after White starts with 1. BxN, Black recaptures with his rook rather than his queen: he’s better off keeping his queen where it can get to the center of the board after White’s next move, RxN. And it shows why Black uses his queen to avenge that last White capture rather

than his d5 pawn: the queen is powerfully positioned on e4 and in this case can grab the pawn on g2 after White does his damage. (c) Finally, when White plays 3. Qg3, why should Black fend off the mate threat with Bf8? Why not, say, f7-f6 or g7-g6? Answer: those pawn moves would allow White to give check when he plays QxR+, thus forcing Black to waste a move saving his king when he should be playing Qxg2.

Dg177: Black to move Dg177: A demanding position. Inspect for unguarded White pieces and you find the bishop (and the queen, but focus on the bishop). Black has no safe way to check the White king and attack the loose bishop at the same time. Does Black have the makings of any mate threats—any pieces already attacking squares next to the king? Yes: the bishop at d7 attacks h3. Next: can Black’s queen attack h3 and the loose bishop at the same time? Yes, with Qh5. That's the idea. But now Black plays through this sequence mentally and finds a problem. If White replies by moving his bishop (say, to b7 or f3), Black does not quite have mate with Qh3+. Here, unlike in the previous problems, the king has a flight square at g1 or h1, and then there is no way for Black’s queen to reach it while maintaining protection from his own bishop. Still, the basic idea looks promising, so keep at it. Where a combination doesn’t quite work, experiment with move order and, above all, be thorough in examining every check and mate threat. We have two sequences to think

about, depending on what White does with his bishop.... (a) Suppose first that White replies to Black's Qh5 by moving his bishop back to b7. We had been imagining that Black now would play Qh3 (and we found that it didn't work). But what other checks are possible for Black instead of that one? There is Qd5 (no good— loses the queen to White's bishop), and there is Bh3. In response to Bh3 White would have to play Kg1 or Kh1. You now ask what comes next, and answer the question by examining every check. There would be just one: Qd1―which leads to victory! How? After White plays RxQ, Black plays c2xR, promoting the pawn to a queen and delivering checkmate. (b) Now let's imagine that after Black starts with Qh5, White moves his bishop to f3 (rather than b7). The initial idea for Black is the same: give check with Bh3. And again White is forced to move his king to the back rank. But this time the follow-up for Black is a little different. He can't play his queen to d1, at least not in one move, because White's bishop on f3 is in the way. So instead Black does it in two moves. He starts with QxB. This gives him a bishop on h3 and a queen on f3, with the obvious threat of mate via Qg2 next move. White's only way to prolong matters is Qb7, so that his queen protects g2. But now Black uses the same little sequence we saw in variation (a) above. He plays Qd1+; and when White replies RxQ, Black recaptures with his pawn, promotes it to a queen, and mates. Of course the point of seeing all this isn't that any of it is likely to happen. You simply are establishing that if White tries to save his bishop after Black starts with Qh5, White ends up mated. So White's best play after Qh5—and the thing you should expect him to do—is to abandon the bishop (e.g., with f2-f3, which at least prevents Black's forthcoming capture from also giving check). This is a harder problem than the previous ones, but it can be cracked with persistence in examining every check and mate threat, and

then every check that would be possible in the subsequent position. And of course you must be alert to the possibility of promoting the pawn on c2. A pawn on the penultimate rank (or indeed any passed pawn) always is a mighty tactical factor; it requires close attention after every adjustment to the board.

a target as a loose piece. Consider it semiloose; it's underdefended. The purpose of this batch of studies is to drive home the idea that pieces in such a position make fine targets. Naturally you could have started your thought process here by noticing that the bishop was vulnerable in this way and looking for ways to attack it while simultaneously threatening mate.

2.2.12. Mate Threats with Attacks on Underdefended Pieces.

Dg179: White to move

Dg178: White to move Dg178: The type of fork we now are studying has two ingredients: a loose piece and a mating threat. You can begin your search by looking for either ingredient, and here looking for the second one—the mating threat—might be easier. There are no loose Black pieces, but White does have a mate threat of the type now familiar to us: his bishop attacks h7; his queen would threaten mate if it were aimed the same way, and this can be accomplished with the easy Qe4. That move also attacks the d4 bishop; too bad it isn’t loose. Or is it? Actually it's attacked once (by the White knight) and protected once (by the Black queen). So if White attacks the bishop again with his queen, he wins it. Normally, of course, Black would respond to such a threat by moving the bishop or increasing its protection. The point of the fork is that it deprives Black of time to do those things.

Dg179: The pattern repeats. You are cultivating awareness of your mating threats, and for White the pattern here is familiar: the bishop at d3 attacks h7; if White’s queen also were to attack h7, he would threaten mate and Black would have to spend a move fending it off. So White plays Qe4, also attacking the bishop on e7. Strictly speaking the bishop isn’t loose, but it's attacked once (by White’s rook, then sitting behind his queen) and protected once (by Black’s queen). So White wins a piece.

Dg180: White to move This problem is structurally about the same as those in the previous set, but with the wrinkle we saw earlier in this chapter: a piece attacked once and defended once—and by a piece rather than a pawn—can make as good

Dg180: Here is a similar position with a bit more to see. What mating threats does White have? The usual: he has the standard bishop attack on g7; White will have a fork if his

queen can attack g7 and a loose piece at the same time. Queen moves to c3, d4, and g5 all are possibilities; the move to d4 looks promising here because it attacks the Black bishop on e4 while also still protecting the White bishop on b2, which you see is under attack. As for Black’s bishop, it isn’t loose but it is protected once by a rook and attacked once by a knight. So if White plays Qd4 and Black replies with some move to fend off the threat of mate, White then will be able to play NxB with impunity. Except that "impunity" is a little too strong. For here is the new wrinkle to observe: after White plays NxB, Black will recapture with his rook and White will take that, too; the purpose of Black’s recapture will be to attract White’s queen away from the defense of the bishop on b2. This way after White plays QxR, Black has QxB. White still has gained a bishop and a rook in return for a bishop and a knight, and thus has won the exchange, but it's important to see this side consequence of the idea. The point: account for the defensive work your pieces are doing before you send them off to make attacks.

Dg181: White to move Dg181: Again we have a familiar pattern with a new wrinkle. White sees that adding his queen’s weight to the pressure his bishop already imposes on g7 would threaten mate. It also would attack the bishop at d6, which now is attacked once and defended once by rooks from each side. But simply playing Qd4 would be a mistake. You have to think out the resulting series of exchanges to make sure it works. After White plays QxB, Black recaptures with RxQ; then White answers with

RxR—and has lost his queen for a bishop and rook! You have to attend to the values of the pieces involved. This pattern worked in the previous frame because Black would have had to sacrifice his own queen in the recapturing process, but that’s not so here. All this means, however, is that the bishop is an unsuitable target; it remains to be considered whether an exchange would improve it. What if White starts by playing RxB? Then Black replies with RxR. Now Qe5 safely threatens both mate and the rook, netting a piece.

Dg182: Black to move Dg182: The initial idea here is familiar. Look for a mating threat for Black’s queen. Black’s bishop at c7 is attacking h2. Qe5 thus suggests itself, as it creates a mate threat against h2 and also attack the knight on d4. The knight is attacked once and defended once, so as we have seen it is a good target for a double attack. But we also have seen that it is important to pay attention to move order. Should Black play Qe5 and plan RxN on the next move? Or should he try RxN first and then play Qe5 after Black recaptures with RxR? This time you find the answer by asking what replies White could make after Black's initial Qe5. Don't automatically assume that White will move one of the pawns in front of his king; another possibility would be to play Nf3—shoring up the protection of h2 and also moving the target of the fork to safety. (You always want to ask whether the target of a fork would be able to jump to safety and block the check—especially when the target is a knight.) The preliminary exchange 1. …RxN; 2. RxR therefore is the way to go; then Black can play Qe5 and win the rook, as there is no way for White to move the

rook and protect against mate at the same time. The previous few problems show the importance of thinking about various move orders. Sometimes, as in this case, these patterns are best resolved with a preliminary exchange that puts a new piece on the target square; sometimes it's best to just play the mate threat and then perform an exchange afterwards— especially if a preliminary exchange would put a new piece on the target square that would be able to defend itself against a double attack. It all depends on how the exchanges would play out. The general lesson, applicable here and elsewhere: don't take move order for granted.

Dg183: Start with the position. Scan for loose Black material and you find the rook at c5 (and the queen; but focus on the rook). White has no way to attack it and give check at the same time, but do not give up; study the Black king’s position carefully. What are the constraints on its movement, and what are its resulting vulnerabilities? It is stuck on the back rank with no defenders there. If White’s queen or rook were to land on the back rank, it would be mate. So the back rank itself becomes a target in just the way that a loose piece would be; White’s goal is to attack the Black rook and the back rank at the same time. What move threatens both? Qb4, winning the rook after Black fends off the threat of Qb8+ (and QxQ# after Black interposes his queen) with a move like h7-h6.

2.2.13. Other Mating Threats. The mating threats considered so far all have involved a attack by the queen on a square already attacked by another piece—typically a bishop. That is the most common sort of mating threat to use as part of a queen fork, but there are others as well; here we'll consider a few examples. Many of them involve an initial move to set up the fork (a check, capture, or threat) followed by a double attack that includes a mating threat. Like the studies toward the end of the chapter on knight forks, they require a willingness to play with the consequences of various checks and captures, always asking about the next check that would be available and looking for familiar patterns to emerge.

Dg183: White to move

Dg184: White to move Dg184: White has no promising checks or mate threats, and only Black’s rooks (and a pawn) are loose. Experiment with captures to see how they and the responses they force would change the board. White has an interesting one available in Nxe5; Black would reply NxN. Evacuating the knight from f3 would open the familiar line for the queen to reach h5, and from there to check the Black king. Qh5 also would attack the Black knight that would then be at e5. At first this looks like a perfect double attack, but actually it isn’t; for consider as well what move you then would make if you were in Black’s shoes. As we recently saw, a common hazard of making a knight the object of a double attack is that it can jump out of harm’s way and block the check at the same time. That would happen here: Black would play

his attacked knight from e5 to g6. But just keep pushing, always asking what lines would then be open and what checks then would be possible. With White’s queen on h5, Black’s knight over on g6 instead of on c6, and the e5 pawn off the board, White has another, more effective attack: recall that the a8 rook is loose; and now White has a fresh mating threat to create with Qd5, adding to the bishop’s existing attack on f7 (remember that a bishop attacking that square early in the game always is a promising setup for a double attack). After Black fends off the mating threat, White takes the rook with his queen. If you look at the original position again you might be able to see the outlines of a fork waiting to happen: if White could get his queen onto d5 and clear the c6 knight out of the way, he would win the rook on a8 by creating a mate threat against f7. But making those adjustments takes a couple of moves and requires the queen to take a circuitous route.

Dg185: Black to move Dg185: White has a loose rook on g5. Black’s queen has no checks, and the mating threat Qd5 doesn’t work because White's rook guards the square (as well as g2). But there are other ways one can threaten mate. Study the constraints on White’s king. It is blocked by its own pawns. Qe7 thus attacks the loose rook and threatens mate on the back rank with Qe1. But this is another of those cases where you have to ask whether White might save the target and defuse the mate threat at the same time. The rook can’t do this by moving, but White does have the simple resource of h2h4, guarding the rook and giving the king an

escape square. Yet as we saw most recently in the previous problem, this sort of possibility should not discourage you. Ask what check would then be possible, and with what consequences. Black could play Qe1+, which would force Kh2. And then what check could Black offer? Qxh4—checking the king and again attacking the rook, and this time winning it. It's all about persistence with checks.

Dg186: Black to move Dg186: The knight on c4 is the important target here—important because it lies loose on the same rank as Black’s queen. Black wonders if he can find a way to attack the knight and White’s king at the same time. The idea would be to get the pawns out of the way between the queen and knight, and to use the g-pawn to support a mating threat by the queen that keeps White busy. Clearing away the White pawn at e4 is the first order of business. Black attacks it with nothing, and anyway capturing would not help because that still would leave the fourth rank cluttered. No, the other standard route is a better way to remove the pawn: capture something it protects, here the d5 knight. Black plays BxN, White replies e4xB, and now the c4 knight is more vulnerable. Next Black needs to move the g4 pawn out of the way and also create a threat with it. The question suggests its own answer: g4-g3 gets the pawn off the fourth rank and also attacks a weak square adjacent to White’s king, creating a threat of mate with Qxh2+ followed by Qh1#. White easily parries all this with h2xg3, but this costs him a move, after which QxN follows. After Black’s BxN, White also has the option of g2-g3, attacking Black’s queen. At first this

looks good; if the queen can be driven away, maybe White will be able to take the Black bishop without the fork Black has planned as a follow-up. But it turns out not to be advisable; for Black has the reply BxNc4, capturing another piece, unmasking an attack by his rook on White’s queen, and aiming his bishop at the White rook on e2. White has to respond by playing his rook to d2, giving it protection and also protecting the queen on d1, giving White a chance to move his queen out of danger with a gain of two pieces. Still, the idea of White's counterthreat (g2-g3) is valuable to see, as is the discovered attack against the White queen that makes Black's riposte (BxNc4) so powerful. We will study discoveries in more detail later.

h3, Nh6; 2. Qe4 wins the rook. (Black would be better off just forfeiting the knight.) The hardest part about this one is seeing that Black's knight would have to go to h6. Remember that a threatened knight often has limited options, and that when it is forced to a new square there may be interesting side effects.

2.2.14. Attacking Two Loose Pieces.

Dg188: Black to move

Dg187: White to move Dg187: What Black pieces are loose? Just the rook at c6, so White looks for ways to attack it while giving check or threatening mate. Qe4 seems awfully close to working; it attacks the rook and, along with White’s knight, threatens h7 for a second time. The hitch is that Black’s queen also protects h7, and White has no way to drive the queen off. Once White sees that only the Black queen stops the winning fork, he focuses on how he might get rid of it—perhaps by harrying it with his pawns. White starts his kingside pawns forward with a threat against Black's knight: h2-h3. Where would the knight go? It turns out to have only one safe square: h6. Ah! The knight then would block the Black queen’s route to h7. Suddenly there is no need to drive off the queen after all; now White's Qe4 would create a serious mating threat because Black’s queen wouldn't be able to help, and the rook at c6 remains loose. So: 1. h2-

Dg188: Queen forks most often have the enemy king on one prong, but of course two loose enemy pieces also can make fine targets for a double attack. Thus diagram above, it is easy if you take the time to ask the right questions. What White pieces are loose? Answer: the bishop at a6 and the rook at h1. Of course you might look for a way to give check while attacking one of them; but don't forget to also ask whether Black’s queen might attack them both at the same time. If the answer isn’t obvious, look for a square where lines leading to both loose pieces intersect, and ask whether the queen can get there. Here Qc6 wins the bishop, since after it is played White only has time to defend the rook. Dg189: Again, there is nothing difficult here if you ask (a) which White pieces are loose and (b) whether there is any way you can attack them at the same time. Here both of White's rooks are unguarded (loose rooks in the corner of the board is pretty common, and make nice targets if the pawns diagonal to them—e.g., the g2 pawn in this example— have been moved).

Dg189: Black to move Look for a square where lines leading to both pieces intersect; see that Qe4 wins one of the rooks.

Meanwhile the pawn on h3 is essential here, too, since otherwise 1. Qe3 is met with the knight fork Ng4+. You want to ask in any position not just whether you have any forks to give but also whether the enemy does—and whether he will have any after the move you are considering. This is particularly important when, as here, Black already has a knight check to give on g4. This means you have to think twice about putting your queen on a nearby dark square where it might get forked. Fortunately it's not a problem in this case because you have a pawn at h3 guarding the forking square.

Dg191: White to move Dg190: White to move Dg190: Here is nearly the same pattern turned sideways. Black has two loose pieces: his rooks. Lines to them cross at several junctures (e.g., g1 and h6), but the only useful intersections are those that allow the rooks both to be attacked on diagonals, making it impossible for them to defend themselves by going after the attacker. So the winning move is Qe3, picking up a rook a move later. This much is easy, at least if you are alert to loose pieces; but now notice a couple of finer points. The fork only works because of the pawns at b2 and h3. Do you see why? The pawn at b2 is critical because otherwise Black could move one of the rooks to protect the other. It always is important to ask whether your opponent would be able to break a fork by moving one of the pieces out of it to protect the other, to check your king, or to otherwise create trouble. It's an especially important issue when you are forking two pieces that both have mobility, as these rooks do.

Dg191: Which Black pieces are loose? Both rooks and the knight. Can White’s queen attack two of them at the same time? Yes, easily via Qd4, winning the knight. Here the queen is just behaving like a bishop; we will see lots of positions like this when we examine bishop forks. By the way, Black has the option of replying to Qd4 with RxNb1, thus limiting his immediate material loss to the exchange. White replies RxR; Black moves his queen to d8 to guard the knight; and now White has e4-e5, a little fork that wins a pawn. Meanwhile White's b1 rook is now in a much stronger position than before. Dg192: Again both enemy rooks—this time the White ones—are loose. Black’s queen can't attack them at the same time, but it can go after one of them with Qd3; so if he could create another target reachable from that position he would have a working fork. The rook

on e1 cries out to be drawn forward with an exchange—such as Bxe2.

Dg193: White to move

Dg192: Black to move If White replies RxB, now both rooks still are loose and can be attacked with Qd3. (White’s best bet is not to recapture Black’s bishop; if he does and then finds himself forked, his most favorable option is Rxe6, at least using one of his rooks to take a pawn on the way down.) By the way, notice the predicament faced by Black’s g4 bishop at the outset here. It's under attack and almost has nowhere to go. If it were to retreat to h5, White would have g3-g4 and would win the piece a move later; if Black instead were to play Bf5, White again traps the bishop with e2-e4. Fortunately for Black he has this other “out” of Bxe2, leading to a queen fork. But you can learn from this near-catastrophe for Black by studying the g4 bishop and the Black pawns behind it. This is a classically poor position for a bishop: its lines of retreat blocked by its own pawns and by the edge of the board. When you see an enemy bishop so positioned, realize that it may be unusually vulnerable to attack. Dg193: Look for loose Black pieces that might serve as targets and you come to the knight at h5 and bishop at d6. Ask if the lines to those pieces intersect anyplace the White queen can reach and you are led to Qd1. Or now think about this position from a defensive standpoint. Black just made the move Bd6, a mistake that turned out to lose him the game in the way just described. How would you avoid making such a move?

By asking the same question about your own pieces that you ask about your opponent’s: which of them are loose, or will be after the move you are considering. And then you treat every loose piece as a vulnerability. In this position Black’s loose knight at h5 already was unfortunate and was a reason to pause before also moving the bishop to an unprotected square.

Dg194: Black to move Dg194: Another defensive study. Black has a problem: his knight on c6 is pinned, and is attacked twice and guarded just once. He is imagining 1. BxN, b7xB; 2. Qxc6+, forking king and rook. So Black thinks about moving his c8 bishop off the back rank to d7, shoring up the protection of the knight. It's a blunder. Remember to ask whether a move you consider will leave anything unprotected. This happened in the previous position when a piece was moved to a square that had no protection. That isn’t a problem here, since the bishop will be safe on d7. But you also want to look at any lines a move affects. The point is the knight on d5. It's protected by the queen. The knight’s protection is cut off if Black plays Bd7; it becomes loose.

Once you see this, it isn't enough to ask just whether the knight now is under attack. Loose pieces can be taken for free by forks. Is your king also exposed to attack? Do you have any other loose pieces? Where is your opponent’s queen? Here your study of those questions would show that you already have an unprotected bishop at c5. So Bd7 would leave two loose pieces right next to each other. And White’s queen is close at hand: on a4, ready to play Qc4 and win one of those two pieces a move later.

to see is that from c1 White’s queen would be aimed at the Black knight on h6.

Dg196: White to move That knight already is attacked once and defended once, which is to say that it’s as good as loose. Adding an attack against it by the queen amounts to a queen fork of Black’s bishop and knight. Black probably responds with the interposition Nc6, allowing White to play BxN next move. Dg195: Black to move Dg195: White’s rook at f1 is unprotected and so is a target, but there is no way for Black to give check and attack it at the same time. Still, when you see any loose piece it pays to think hard about ways to attack it and create problems elsewhere with your queen. Here Black’s queen can attack the rook with Qc4, which also attacks the knight at h4. So examine the knight’s situation and notice that it is attacked once and defended once, and defended by a piece rather than a pawn—as good as loose, as we have seen elsewhere (you might just as well have spotted all this by regarding White's knight as a good target from the outset). Qc4 thus wins the knight, because after White moves the rook Black plays BxN and White dares not recapture. (If White replies to Qc4 with Qf2, protecting his rook, Black plays BxN just the same.) Dg196: A loose piece can make a fine target even when it lies in its original position on the back rank. Here Black’s bishop on c8 is loose; White can attack it with Qc1. But this only is interesting if the attack can be paired with a simultaneous threat elsewhere. The key point

We have seen many times the importance of being aware of loose pieces. But it likewise is important to be aware of pieces attacked once and protected once; they often make targets for forks that are just as good as pieces with no protection at all.

Dg197: White to move Dg197: A cursory look at White’s attacking options turns up Rxb7, taking a pawn for free. But even when you have a simple capture available it's worth asking whether you might have something still better. Standard procedure for the purpose, of course, is to experiment with any checks you can give; safe checks with your queen are especially impor-

tant because they may in effect give you a free move. Here White has one in Qd3. It forces Black to move his king to the back rank or play g7-g6. Either way, ask what White could do next. Answer: fork Black’s rooks with Qd7, taking one or the other of them a move later. Of course another way to see this is by scouting for loose pieces on the board. Two loose pieces, as Black has here—and on the same diagonal, no less—beg to be forked. You see that your queen needs two moves to get to the forking square; so you ask whether you can make the first move a check that will keep Black busy. This leads to Qd3 as a transitional move. A natural mental sticking point here is to start looking at the check Qd3 and then give up when you conclude that you then have no good follow-up against Black’s king. The trick is to be flexible enough in your thinking to move from looking at checks against the king to looking at follow ups against other pieces. In this case the power of the check Qd3 isn't that it forces Black’s king to change squares; it's just that it gives White a way to move his queen across the board while denying Black a chance to respond. Anyway, if you are conscious of the two loose rooks in this position you won’t overlook 2. Qd7, because you will be thinking all the time about how to get at them.

2.2.15. Attacking Two Loose Pieces: More Procedures.

Dg198: White to move Dg198: How many Black pieces are loose in the position ? None (setting aside the pawn at e5). Nor does White have any productive checks. But we also want to examine the results of every capture. RxB is the only one White has to consider; it results in RxR. Now how many Black pieces would be loose? Two: both rooks. The problem then becomes the easy one of finding a square—c6—from which White’s queen can attack the rooks simultaneously. Ask what Black’s response to Qc6 would be; might it be possible for one of the rooks to rush to the defense of the other? No, but only because of the placement of some pawns: the b3 pawn prevents either rook from moving to a4, and the e5 pawn prevents Ra8-e8 from being useful. If either pawn were missing, the fork wouldn't work. That's one lesson of this problem: the importance, as we have seen elsewhere, of considering whether one forked piece can move to protect the other. The other lesson is that a single exchange—here, 1. RxB, RxR—can radically change the board; in this case it moved Black from having no loose pieces to having two of them.

Forks that attack two loose pieces can run into most of the same obstacles as forks that include checks on the king. There is no need to catalogue them exhaustively here; once you've found a forking square, the task of loosening it for occupation by your queen generally is the same regardless of whether the fork involves a check, a threat of mate, or an attack on two loose pieces. But here are a few examples of how the familiar problems discussed earlier look in this context. Dg199: Black to move

Dg199: Black recently moved his bishop to a3; then White took it with his b-pawn. Now it’s Black’s turn again, and time to figure out why he let his bishop get taken. Look for loose White pieces and you come to his rooks—and see that the diagonals leading to them now are open on both sides. Black can't attack them both at once, and he has no checks or useful captures to consider. But it's important also to consider threats, since the replies to them tend also to be forced; they let you hold the initiative and control the play. Here you ask which Black pieces can attack either White rook. There is only one answer: Qd4. It doesn't win anything by itself, but ask anyway what will White play in response. Suppose he moves the rook to b1. Now ask the same questions: you still are trying to make something out of the two loose Black pieces—and now you can attack them simultaneously, with Qe4. (White’s better reply to Qd4 thus is Bb2, interposing his bishop; it gets taken next move—for now it, too, has been left loose—but then White at least has a move to save his rook.) This position is a good example of a point made earlier: a rook frequently is unprotected when it sits in the corner of the board, and so is vulnerable to a fork if its diagonal pawn cover is blown. This is an unusual case where both rooks are in that position. Think about it if you or your opponent moves the pawns at b2, b7, g2, or g7 early in the game.

camp: the rook on c8 and the bishop on h6. His immediate thought is to pair an attack against one of them with an attack on Black’s king, or to attack the two of them at the same time. The natural weapon for either purpose is the queen. It's well-positioned for action on g3. White looks for a square from which his queen could take advantage of the loose Black material and sees that Qh3 aims the queen at both bishop and rook. The only hitch is the pawn in the way on e6. The usual procedure for removing a bothersome pawn is straightforward: take something it protects. Thus White begins with RxB, inviting the recapture e6xR; now Qh3 forks the loose Black pieces and takes one of them next move, winning two pieces for a rook (and leaving White ahead by a whole piece, as he already was up the exchange). It all would be even better, by the way, if White’s rook were on d1 instead of d2. In its actual position here White’s rook is en prise to the bishop on h6; so if White starts with Qh3, Black has BxR. If the rook started on d1 there would be no such threat and White could make Qh3 his opening move. The move isn’t quite a fork, but it threatens the loose bishop on h6 and also pins the pawn on e6, thus creating a fresh loose piece on d5. Black most likely would respond by moving the h6 bishop to safety on f4 (Kg7 is another possibility); and then White can play RxBd5, winning a piece cleanly since Black won’t recapture (if Black does play e6xR, White has QxR and still has the piece). We will examine the creation and use of this sort of pinning move in a later section of this project.

Dg200: White to move Dg200: It's hard to overstate the importance of loose pieces in chess—noticing them, creating them, and exploiting them. Loose piece = target. Here White sees two in the enemy

Dg201: White to move

Dg201: How many Black pieces are loose? Two: both knights. There is no way to attack them at the same time, and no way to attack either of them while threatening the king in some way. Those loose pieces nevertheless are tantalizing targets, so White starts digging for ways to attack one of them and something else of value at the same time. The simplest way to do this is by just looking at squares from which the queen can attack either knight, and then seeing what else can be attacked from the same squares: if not a loose piece, then perhaps a piece that can be made loose. White’s queen can attack the g3 knight by moving to c3 or d3. From d3 the queen also would attack the bishop on a6. That piece isn't loose, and anyway it can strike back at d3. Since White has a target, but one that doesn’t work, he looks for an exchange that would improve it: he can play BxB, provoking RxB. Now d3 has been made safe for White queen and Black has a loose piece— the rook—on a6. Qd3 thus attacks two loose pieces and wins the knight. You also could have found this by just examining every capture of a piece by a piece that you can initiate: imagine 1. BxB, RxB; ask whether that exchange leaves behind any loose pieces; see that the rook would then be loose; look for ways to attack it along with another loose piece; find Qd3. Either way, this problem resembles the earlier ones where White’s queen had a clear path to a square from which it could attack the king, but needed to loosen the other target with a preliminary exchange to create a good double attack. In other words, imagine that the g3 knight in this problem is the Black king, and the rest of the problem then becomes structurally the same as many we saw earlier in this chapter. The implication: if your queen can attack a loose piece and any other piece, start asking whether the other piece can be loosened (or replaced with something loose) as well. Dg202: This position may seem elusive if you flail about at random, but it comes apart easily with methodical interrogation. Which Black pieces are loose?

Dg202: White to move The bishop and both rooks. (You might look for ways White’s queen could attack any of them and also the king, and come up empty: the needed squares—e.g., d4, d7—are protected.) Since there is more than one loose piece, try attacking two of them at once. Look for a square from which this could be done safely with the queen. You attack rooks from diagonals and bishops from ranks or files, so that the targets can't strike back. The h4 rook and e6 bishop could be attacked from e1, or— if the king weren’t protecting it―from f6. The queen can’t reach either square in one move, so see if it can get there in two moves, with the first one a check or other threat that controls Black's response. Qc3+ requires the Black king to move to h7; then Qe1 forks the rook and bishop. Black can't escape the loss of a piece. (If White instead plays the forking move Qf6, Black can use the rook to protect the bishop: Re4.) You also could have found this by just examining every check. The queen has checks at c3, d4, d7, and g6. Only c3 is plausible; all the others result in the queen being captured without an adequate follow up. So you ask what would be possible after the king is forced to move. You are mindful of (a) any loose pieces, (b) the king’s new position on h7, and (c) the White queen’s new position on c3. Qe1 then is simple enough. Dg203: White has no checks or captures to consider. There remains one other sort of forcing move that at least partially dictates the enemy response: a threat, especially by a pawn; these tend to be very effective forcing moves because your opponent generally can't

afford to lose a piece for a pawn. So try e2-e3. Where will the Black knight go?

Dg204: White to move

Dg203: White to move Look at the ring of eight light squares within its range, and see that only two of them are safe: b5 and f5. As usual after any sequence, you then ask what pieces would be loose, what lines would be open, and what attacks would be possible. Here the knight and bishop both would be loose (surely you saw the loose bishop from the start), and the movement of the e pawn would have opened a line for the queen. It is urgent that White look for ways to take advantage of those two loose pieces in the middle of the board. If the knight moves to f5, White can use the new open line to play Qg4, attacking knight and bishop at the same time. If the knight moves to b5, White can attack both pieces with Qa4. The most important things about this problem are (a) not to overlook threats by pawns; they are forcing moves, and can cause big changes on the board—loose pieces and open lines; (b) to remember when thinking about White's second move that the e-pawn would be out of his queen's way; and (c) not to just assume the Black knight will “move somewhere” if attacked, but instead to examine its actual options and patiently consider what you could play in response to each of them. If the position were slightly different the fork at the end might not have worked; the knight might have been able to retreat to a safe square. But the benefits for White if the Black knight does end up loose are great, so a careful study of where the piece can go is fully warranted.

Dg204: Two Black pieces are loose: the rook at a8 and knight at h5. Look for a square from which the queen might attack both. The lines to them intersect at e8 (way too hard to reach) and d5 (more feasible—White’s queen can get there in one move). The only problem is that the pawn on c6 both blocks the path to the loose rook and protects d5. We handle this with an exchange, of course, drawing the c6 pawn forward by capturing its protectorate. 1. Nxd5, c6xN and now the problem is in simpler form; you see that d5 is occupied but unguarded and the paths to both rook and knight are clear. Qxd5 suggests itself as a working fork. But now pause and reflect on Black's reply to Qxd5. One of his forked pieces, the knight on h5, is positioned aggressively. Black might be able to break out of the fork by using that knight to do some damage. Indeed, he might play NxBf4; then if White carries out the fork with QxRa8, Black has Nxe2+, a fork of his own. So to prevent all this White doesn't follow 1. Nxd5, c6xd5 with Qxd5 right away. He first moves that vulnerable bishop off of f4, and he does it with a threat that holds the initiative: Bc7, attacking Black's queen. Notice that the bishop has protection on c7 from the rook back on c1, because Black's c-pawn is gone by that time. Black thus moves his queen—and now White can go ahead with the queen fork on d5, because Black can't use his knight to make a capture in reply; the piece he might have wanted to capture—White's bishop—is no longer there. If Black is alert, of course, he will not recapture on d5 in the first place; he will let the

pawn go rather than subject himself to all that has just been described. As often is the case, the value of the threatened fork is that it permits other, lesser gains by making it too costly for your opponent to recoup his losses. (Here Black can reply to Nxd5 with NxB, removing his loose knight from the coming fork; then White has Nd5xN, keeping the pawn.) It all starts simply: by noticing loose pieces and asking whether you can make a double threat that includes at least one of them. If you do that, seeing the fork is reasonably easy. If you don't, it's hard.

no matter how short; likewise keep track of the open lines left behind by any forcing sequence you can find, no matter how short.

2.2.16. The Enemy Queen as a Target. Usually your opponent's queen makes a poor target for a queen fork because it can defend itself by attacking the attacker. Part of the beauty of the knight fork is that a knight, on account of its unusual pattern of movement, can attack an enemy king and queen without being subject to capture by either of them; the queen as an attacker generally does not have that advantage. The exceptions are cases where, if the attacked queen does defend itself, the result is mate—most commonly on the back rank—or else another combination.

Dg205: Black to move Dg205: Start with a routine inspection for loose White pieces; find the bishop at c1 and rook on e8—and then focus on the bishop. Black has no checks that also attack the piece, so he plays with other forcing moves. He has only one capture to consider: BxB, to which White would respond KxB. When you ponder such an exchange, think about what pieces would be left loose and what lines would be opened by it. The answer to the question about loose pieces is that the king’s move to h3 would leave a loose knight on h1; the answer to the question about open lines is that taking the Black bishop off the board opens a clean line for the Black queen to g1. Put these points together with the loose bishop at c1 and we have an easy double attack against two loose pieces: Qg1 wins the knight. Notice how the same principles emerge time and time again: keep track of the loose pieces on the board, but also the pieces that are left loose by any forcing sequence you can find,

Dg206: White to move Dg206: In this first example, start by examining the Black king’s position and the constraints on its movement. It is stuck on the back rank. White can launch an attack there with his rook on the e-file; if the Black queen weren’t in the way, Re8 would be mate. “If his queen weren’t there, I could mate”—many combinations begin with a counterfactual like this, which is why imagination plays such a large role in chess. Here the point of the insight is that Black’s queen is unusually vulnerable to attack because of the crucial defensive work it is doing. It also is loose, and so is Black’s bishop, so White looks for ways to attack them at the same time. Their lines intersect at b4, so White plays 1. Qb4. If Black plays QxQ, then White ends the game with Re8#.

We aren't quite done with the analysis. After 1. Qb4 Black will look for some other way to save his queen and avoid disaster. What will it be? Moving the queen to c8 where it seems to protect the bishop is no good, of course, since play then goes 1. Qb4, Qc8; 2. QxB, QxQ— followed, again, by 3. Re8#. Black might instead move his queen to a safe square like g8, but his best reply to Qb4 probably is Nc6. Do you see why? It opens a line from Black’s rook on a8 to his queen, so that the queen no longer is loose. Now White has a choice of 2. QxB or 2. QxQ, RxQ; d5xN. Either way he wins a piece, but the latter sequence is a little stronger because it also takes both queens off the board, magnifying the significance of the advantage White gains.

But then White has 2. RxR, QxR; 3. QxN, still winning a piece. Think of our current theme this way. We have been studying double attacks; these are simultaneous attacks on two vulnerable points at the same time. A loose piece is a vulnerability, as is the king. If you attack them at the same time, you generally win one or the other. We also saw that even a mere square can be a vulnerability if the queen would deliver checkmate by landing on it; attacking such a square—and thus creating a mating threat—can be as good as attacking the king itself for purposes of creating a double attack. Now we are adding still another point on the board that qualifies as a vulnerability: a queen that is defending against mate. Once you see this—once you identify a way that you could deliver mate if it weren’t for the enemy queen—then attacking the queen becomes itself a kind of mating threat. The usual worry, which is that if you attack the queen it will bite back, is out of the picture.

Dg207: White to move Dg207: The principle here is similar. Black’s queen is loose. As a matter of course you also study the constraints on the enemy king’s movement and ask whether you have any sort of mating threat in view. Again White nearly has a mate on the bank rank: if the Black queen leaves its post, RxR is checkmate. In effect the queen is stuck where it is; the protection it provides the knight is illusory, so the knight is as good as loose. Look for a square from which White’s queen can attack the knight and queen at the same time, taking advantage of the queen’s paralysis. The search leads to Qf7. If Black replies QxQ, White plays RxR#. So instead Black plays Qc8 or Qb8, and White takes the knight. (If Black then plays QxQ, once more White can play RxR#. Here as in the previous problem, the queen is committed to guard duty on the bank rank.) Or 1.Qf7 can be met with 1. ...Kb8, which gives Black's queen a guard.

Dg208: White to move Dg208: What Black pieces are loose? All of them: rook, bishop, and queen. What sort of shape is Black’s king in? Not so good: once more it is stuck in the corner behind its own pawns with no defenders on the back rank. Rd8 would be mate if it weren’t for the Black queen defending that square. This fact should ring a bell: the queen is preventing mate. So White looks for a way to build a double attack against the queen and something else. The natural second target is the loose rook. White can play Qe5 or Qe3, attacking both queen and rook; these moves look brazen, but if Black plays QxQ White plays Rd8 and it’s

mate (after Black uselessly interposes his queen and rook and White’s rook takes each of them). So Black responds to Qe5 by retreating his queen to avoid mate—or, better, by moving his bishop to e6 to block the attack. White then wins the rook. The initial step in all these positions is to see if you are anywhere near threatening mate— and this includes mate threats that would exist if it weren't for the enemy queen. These can be hard to notice because mate looks so impossible. The queen prevents it, and your mind stops there. But now you will be more likely to spot such cases anyway because you realize what they mean: the queen itself can become a fine target.

Dg209: White to move Dg209: Examine the Black king’s position. If White safely could play RxR on f8 the game would be over; but Black’s queen guards the rook and so prevents this. This makes the queen vulnerable to attack, as it cannot afford to leave its post to defend itself. Consider ways of going after it. If White attacks the queen with Qc2, Black can reply by simply moving it to d6 where it still does the same defensive work. White needs a way to threaten Black’s queen while also threatening something else. Black’s other pieces have guards or are inaccessible, so what else can White threaten? Again, focus on Black’s king. White’s rook not only threatens RxR; it also attacks a square next to the king (g7). If White’s queen were aimed at that square, it would threaten mate. So White does have a double attack: with Qe5 he can attack both g7 (a mating square) and Black’s queen (another vulnerability—it can’t strike back). Some-

thing has to give, and it’s the Black queen. Black plays RxR to avoid mate, but then suffers QxQ and the game is over anyway. The point, of course, is that once the enemy queen becomes a good target for a fork because it can't afford to move, you can combine it with all sorts of other threats: attacks against other loose pieces, attacks against the king, or—as here—attacks against mating squares. To see this last option you need to be alert to multiple mate threats you can make. By assumption you already see one—RxRf8; that's how you realized that Black's queen couldn't move. The trick is to remember there might also be a different one that then can be made the basis of a fork: you can add a threat by your queen against g7. Notice, finally, that the same effect could be achieved in a more roundabout fashion by pursuing that first idea—Qc2—a little farther. We saw that Black can reply with Qd6; but then if White plays Qd2 he attacks Black’s queen again. Black moves it back to c5, creating the same position seen in the diagram but with White’s queen now on d2 instead of e2. White then can play Qd4, again forking Black’s queen and the mating square g7. The reason to bother noticing this is just to remember that sometimes there may be more than one forking square and more than one way to get there. Since perfecting such a fork ends the game almost as surely as checkmate, it is worth carefully studying all the ways you might make it work.

Dg210: White to move Dg210: This position only sort of fits in this section, but it's instructive nevertheless. On a8

Black has left a loose rook with an open diagonal running toward it. White has no good mating threats but his knight is in an intriguing position: it attacks e7, from which square it would check Black’s king. Be alert for forks anytime the knight is one move from attacking the king. Meanwhile White looks for ways to threaten the loose rook and sees that one of them is Qc6, which attacks both rook and queen and requires a reply: perhaps QxQ. Ask how the board would look after that small sequence, and notice that Black’s king and queen both would be on light squares— ready to be forked with NxB, which wins the bishop for White when the smoke clears. Now don’t forget to ask whether Black’s queen, when attacked by White’s queen, could both move out of harm’s way and defend the other attacked piece. Suppose, for example, that instead of playing QxQ, Black plays Qb8. Now White’s queen can’t take Black’s queen or rook. But—aha!—the bishop at e7 would be left loose by the queen’s movement, so White could play NxB with impunity. If Black instead had played Qd8 so as to protect both bishop and rook, White again envisions NxB. Black could answer with QxN; but then the rook would be loose (Black can’t have it both ways), and QxR+ takes it. So the result is that Qc6 is a working queen fork of Black's queen and rook—though this time without a mate threat in the background. Instead it works because Black's queen is vulnerable for a bunch of other reasons: it can move only at great cost, because it is doing other defensive work (guarding the bishop and rook) and because if it captures on c6 it lays itself open to a knight fork.

2.2.17. Summary; Strategic Implications. Now consider some strategic implications of our study of queen forks, along with summaries of several repeating ideas: 1. Appreciating the power of checks. An important purpose of many strategic moves—

moves spent improving your position, rather than attempting to win material—is to create fertile conditions for tactical strikes on your part and poor conditions for them by your opponent. We have seen that a common form of one tactical idea—the double attack by the queen—involves a check of the enemy king coupled with an attack on a loose piece. The defensive moral for strategic purposes is clear: beware any position that allows your king to be easily checked. It is common for a beginner to imagine that open lines to his king are not a big problem so long as the king easily will be able to escape any threat that emerges, or so long as the opponent only has one piece to threaten it. Not so; the check itself is a menace, no matter how easily it can be escaped, because it requires a timeconsuming response. The more ways your king can be checked, the more ways there are for you to lose other pieces to double attacks. This, and not just the fear of checkmate, is one of the reasons why it is important to castle early; it also is one of the reasons why you should not casually disturb the pawns in front of your king, since you then create open lines that make checks and mating threats—each of which may be half of a fork—easier to create. To turn the point around, one of the general goals of this chapter and the others is to change the way you think about checks. They are immensely useful weapons in the tactician's arsenal not because they annoy your opponent or necessarily lead to mate but because (a) they require responses, thus leaving your opponent no time to address any other threats you have made at the same time, and (b) they require predictable responses, and so allow you to foresee and control the action on the board. 2. Captures. Think of captures in a similar way. Don’t look at a possible capture you can make, see that your opponent can then recapture, and then decide it’s not worth pursuing; rather, imagine the way the board would look after the capture and ask what you then might be able to do: what checks would be possible; what pieces would be loose; what lines would be opened; what further captures could be

made, and where they would lead—all the time searching for a double threat. 3. Mating Threats. We have seen many times, too, the power of mating threats. This points up the strategic value of aiming your pieces in the direction of the enemy king. Directing them this way creates not only the possibility of actual checkmate, but also a favorable climate for threats you do not expect to carry out but that allow you to make trouble elsewhere at the same time. You also can see now that exchanges or threats that open lines to the enemy king create promising conditions for tactical moves because they make making mate threats easier to build. It doesn't matter that the mate threats are easily met. So long as your opponent has to spend time addressing them, they do their work, which is to buy you a free move to capture something loose elsewhere. All these points may amount to a new way of thinking about the moves you make: treating captures and attacks on the king as means to achieve other ends, not just as ends in themselves. There are smaller examples of the same point, too. A beginner decides whether to move a piece from square A to square B by asking what the piece will do on square B. The experienced player knows that the move may be more important because it vacates square A and any lines that ran through it, and blocks any lines that run through square B. Those consequences may be good or bad. The important point is to grasp them. Make yourself a student of indirect as well as direct consequences of chess moves. 4. Loose Pieces. We have seen as well the immense importance that loose pieces have for the tactician. One of the strategic implications of this can be analogized to military strategy: it is dangerous to overextend your forces, letting them wander into enemy territory with little or no protection. Those pieces can be taken for free if the enemy can make them the subject of a fork. You therefore should pause before sending a piece into your opponent’s half of the board with no protection, or protection only from another one of your pieces—even if you are putting it on a

square not currently under attack. And from a defensive standpoint this suggests the value of denying outpost squares—squares wellprotected by enemy pawns—to your opponent. If he wants to advance his pieces, make him put them where they will be loose, or where they only can be guarded by his other pieces, not by his pawns. Then maybe those guards can be exchanged or lured away, leaving the first piece loose. (A pawn that protects a piece is harder to deal with; getting rid of it by exchanging it for a piece often is too great a sacrifice to be worthwhile.) 5. Defending the King. The tactical principles we have studied also shed light on the value of some basic ideas about good play, such as the aforementioned importance of castling early, and of keeping a defensive piece or two near the king. Without any defensive pieces in its vicinity, the king is left to defend its own pawn cover, which means the squares where those pawns sit are weak, which means it is easy to force the king to move by taking one of those pawns and easy for a mating threat to be set up against them. Maybe the mating threat can be thwarted easily once it arises by moving one of the pawns forward, but again that may be too late to prevent another piece from being taken if the mating threat was half of a fork. Likewise, preventing the enemy king from castling by forcing it to move early in the game can be very damaging, because after some exchanges in the center it may then become easy to throw checks at the king while also attacking other pieces. 6. Shedding light on some openings. Still another example of how tactical principles shape strategic decisions: now you can understand why formations like the King’s Indian Defense (or Attack) are so useful defensively. Think back to the many forks we saw that involved mating threats aimed at g7 or h7 (or comparable squares on White’s end of the board). Mating threats against those squares often suggest themselves because those squares are so weak; as just said, after castling they often are protected only by the king, so it is easy to line up a bishop and queen against them in a way that requires a moveconsuming response. In the King’s Indian

formations (look at the position of Black’s king in the diagram to the left), mating threats are harder to create. The h7 pawn has another pawn in front of it at g6, insulating it from attack on the diagonal. And the bishop at g7 makes it hard to set up a battery against that square, either; unlike a pawn, the bishop can lash out against an enemy bishop or queen lining up to attack it. Naturally these features are just one advantage of the King’s Indian formations, and depending how a game goes they may not be important. The broad point is just that tactical insights often can help you understand the purposes behind an opening. 7. A style of thought. Finally, the studies in this chapter are meant to help you develop a more active and aggressive attitude at the board. Now that you see the usefulness of open lines and loose pieces, you naturally will be vigilant in searching for them and creating them: making exchanges that will leave unguarded enemy pieces in their wake or create open lines to the king; making pawn moves that open lines for your queen and other pieces and that close off lines for your opponent; coordinating your pieces to build mating threats that you may or may not be able to carry out but that might enable you to win material with a double attack. The chessboard comes alive with these sorts of thoughts once you understand how they can translate into tactical payoffs.

Dg211: White to move

2.3. The Bishop Fork.

2.3.1 Introduction. We have seen that if you want to spot and create double attacks for one of your pieces, it helps to have a clear understanding of what its natural targets are. In the case of a bishop fork (pictured to the left), as with queen forks, the most common targets are the king at one end of the double attack and a loose piece on the other. There are exceptions, of course, and we will consider them, but this is the most usual pattern and the most important to master. The reasons why this pattern is most common are by now familiar from our other work on double attacks. Consider the impediments to a fork by the bishop—the reasons why attacking two pieces with your bishop might not work. One of the forked pieces might be able to capture the bishop if the bishop’s square isn’t protected; one of the forked pieces might be able to break out of the double attack by making a separate threat of its own; the more valuable or less protected of the forked pieces might be able to move, leaving at the other end a piece that has protection (or moving to protect it). But all these possibilities tend to be reduced when the king is one of your targets: your opponent is required to address the threat rather than saving the piece at the other end of the fork; nor does he have time to use the piece at the other end to make a counterthreat; and because of the king’s limited mobility, it usually cannot fight back itself against the forking bishop or launch a counterthreat of its own. And of course a loose piece at the other end of the fork is ideal because it can be won for free. It just can't be a bishop, for the same reason a knight is an unsuitable target in a knight fork: it can bite back against its attacker. Our method of finding double attacks by the bishop, then, generally will resemble those we've developed elsewhere: searching for checks the bishop can deliver and pieces it can attack at the same time; and working to expose the king and loosen enemy pieces to create chances for those checks and attacks.

The methods will be easy enough if you have read the chapter on queen forks. Whereas a queen sometimes may be able to check an enemy king in four or five different ways that need to be considered, the checks a bishop can make usually are limited to one and never can be more than two; and since each bishop runs on squares of just one color, only one of your bishops can possibly give check at any given moment. Examining a bishop’s checks therefore is quick and easy.

Dg212: Black to move Indeed, you can think of a bishop as a little like half a queen; it can make the same diagonal moves a queen can make, but not the horizontal and vertical type. Every move we will see a bishop make is a move a queen also could make. But not necessarily a move a queen would make; for the bishop has the advantage of being worth less than the queen, and thus easier to sacrifice. Giving up the bishop to win a protected rook makes sense, whereas giving a queen for the purpose does not. We can use this point to add to our list of targets for forks by the bishop: not only kings and loose pieces, but also rooks whether they are loose or not. A rook always is a good target for a bishop, because (a) it is worth more and (b) its pattern of movement makes it unable to strike back at a bishop that attacks it. Some bishop forks require not only that the forking square be available, but that the bishop be protected. Such protection generally isn't important when building knight forks because their targets (kings, queens, rooks, bishops, pawns) don't move in ways that allow them to strike back at a knight. Protecting the forking square also is unlikely to

be important when creating a queen fork; if your queen can be taken, the fork probably won't be worthwhile regardless of whether you can recapture the piece that takes it. Bishop forks differ from those types because sometimes a bishop fork will include the enemy queen at one end of it. Since queens can move like bishops, a queen always can capture a bishop that attacks it—unless the bishop is protected. So this is the last point about the targets for double attacks by bishops: the target can be a queen if the bishop has protection. To sum up, double attacks by the bishop generally involve some combination of these targets, listed in rough order of frequency: the king; a loose knight; any rook; and the queen if the bishop has protection. (Loose pawns are fine, too, of course.) Since some of the techniques for making a bishop fork work are similar to the techniques shown in the chapter on queen forks, the coverage of them here will be a bit more brief.

Dg213: White to move There are a couple of other variables to think about as you study the bishop. The most important involve the geometries involved when the bishop inflicts a fork and the visual patterns that result from them. We didn't emphasize this as much in studying queen forks because they can occur in so many ways that have little in common visually. But double attacks by bishops require certain conditions that often have a distinctive look. A bishop fork most often occurs when your opponent has two pieces on the same diagonal with nothing between them; when the bishop

moves into position, the three pieces all are in a line (the position diagrammed in skeletal form in the previous frame). It therefore is important to train your eyes to spot any two enemy pieces on the same diagonal— especially if there isn’t anything between them, but even if there is. This is a good habit for other reasons as well: pieces on the same diagonal may also be subject to a fork by your queen, or may be prey to a pin or skewer (possibilities considered elsewhere). The same goes for enemy pieces lined up on the same rank or file: they may be forked by one of your rooks, as we will see in another chapter; sometimes they may be forked by a bishop, as we will see in a moment; and they may also be subject to a pin or skewer. Diagonals will receive a lot of attention in this chapter because that is where bishops travel, but the general point is that pieces on a line of any type are important to spot. There is another type of bishop fork that looks different and can occur when your opponent has two pieces on intersecting diagonals. When the fork is executed the pieces are arranged not on a line but in a triangle. A fork of this kind almost always results from a capture by the bishop on the square that forms its corner of the triangle; before the capture, the bishop was aimed at one of the pieces targeted by the fork, but an enemy piece blocked the bishop’s path to the target (it might be a pawn, as in the diagram to the left where White is about to play the fork Bxd6). Another way to say this is that before the bishop captures, there are three enemy pieces in a triangle, all on squares of the same color; the bishop captures one of them and forks the other two. (Again, see the diagram.) These patterns are important to study because to the untrained eye they don't look like the makings of a fork by a bishop. But they are; they are poised to be forked in triangular fashion. The easiest and most common examples of the triangular pattern arise when two enemy pieces are on the same file or rank, often the back rank, with an odd number of squares between them.

Dg214: White to move Dg214: Start with the simple case of two pieces on the back rank separated by one square—the Black king and rook in the stylized diagram (the diagram is just meant to illustrate how some different bishop forks can work; it doesn't call for consideration of what White should actually play). Black's king and rook are arranged to be forked—by a knight at e6, or by a bishop (or queen) at e7. In the bishop’s case there generally will be an enemy piece already on e7—here, the pawn; otherwise the bishop would be able to take the target piece—the rook—without need of a fork. Now spread the targeted pieces three squares apart (the White king and c1 rook in the diagram). Again a fork is indicated—by a Black knight at e2, or by a bishop or queen at e3. And a bishop (or queen) fork again is possible if the targets are five squares apart, like the White king and a1 rook. A queen can do the job by moving in directly—say, from d5 to d4 (imagine the White pawn on d4 rather than e3); a bishop can do it by taking an enemy piece sitting on d4, and in this latter case the enemy pieces again will be arranged as a triangle at the outset. And of course all this can happen on a vertical file as well as on a horizontal rank. The horizontal formations just are more common because the pieces start out arranged that way on the back rank and often stay there for a while. The types of triangles just considered are relatively easy to see once you know to look for them because they have a regular, almost equilateral appearance. But even the more oddly-shaped triangles can be found by ha-

bitually looking at what the bishop already attacks—the line of enemy pieces that lie ahead of it on any of the diagonals it commands, and what else it can attack by taking one of them. (See the diagram, where the Black and White bishops each have a fork via a pawn capture that creates an unorthodox triangle.)

wins. Another way to have seen this would be to ask which Black pieces are loose, which leads to the rook; the only way White can attack it is with Bc4, which also checks the king. A final way would be to just see that the king and rook are on the same diagonal with nothing between them. This visual configuration cries out for a double attack by a bishop (or a queen acting like a bishop).

Dg215: White to move Dg216: White to move What does all this mean for practical play? It means you will want to scan the diagonals on the board—and the ranks and files, too—for pieces lined up on them. This is especially important when one of the pieces is a king. Also be alert for triangles, and relatedly for enemy pieces scattered about the board on the same color squares. A bishop can of course fork pieces only if they travel on the same color squares that it does; and almost any two enemy pieces on squares of the same color can, in principle, be forked by a bishop from some other square on the board—“almost” because there is no way to fork two pieces next to each other on the same diagonal. The general point nevertheless is useful, and reinforces a lesson from the chapter on knight forks: pieces on squares of the same color tend to be most vulnerable to double attacks of various kinds. Watch for them.

Dg217: White to move

2.3.2. Bishop Forks One Move Away.

Dg217: What checks does White have with his bishop? Be4. Does the move attack anything else? Yes, it attacks and wins Black’s rook, which is loose. This position looks easy, and it is; but again, absorb the look of it for a minute. It is important to appreciate the use of the fianchettoed bishop (on the square in front of the king) to execute a fork. Later in the chapter we will see this same position again, but two moves earlier.

Dg216: What checks can White give with his bishops? Two: Be8 (resulting in KxB—not very appealing), and Bc4, which at least is safe. Does the bishop attack anything else from c4? Yes, the rook at a2—which White

Dg218: Look for bishop checks and you find one: Bxc6. Ask what else the move attacks and you find the loose knight on e4. So Black moves his king and White wins the knight. That is the target-based way of seeing the

Now on to some examples.

solution; the pattern-based way would be to notice the triangular relationship between Black’s king, knight, and c-pawn, all on White squares. Stare at the diagram; contemplate its appearance.

bishop, the fork only works if the bishop has protection on d4. It does, from the Black rook on d8. So Bd4 trades the bishop for White’s queen. Now try seeing the pattern by scanning the geometry of White's pieces; it is important in a position like this to notice right away that White's king and queen are on the same diagonal. Again, it will help to take away two types of lessons from these positions: conceptual points (trains of thought that lead to the forks) and visual patterns that you will be able to recognize in your games.

2.3.3. Loosening the Forking Square. Dg218: White to move Incidentally, what comes next after White plays 2. BxN? Now his bishop attacks both rooks—this time on the same diagonal—and so wins one of them as well. Again, you could see this by asking what the bishop attacks, or you could see it by scanning Black’s pieces for promising patterns and noticing that Black’s two rooks are on the same diagonal, just waiting to be forked if White can take the Black knight with his bishop. He can best do that by advancing on the knight in a way that also gives check (i.e., with Bxc6+), thus requiring Black to address the threat to his king rather than defuse the coming fork of the two rooks.

Dg219: Black to move Dg219: Inspect for checks Black can give with his bishop; this turns up Bd4. Does the move attack anything else? Yes, White's queen at b6. Since the queen can attack the

Dg220: Black to move Dg220: What checks does Black’s bishop have? Bd4. Look to see what else the move does and note that it attacks the loose rook at a7. So there is a potential bishop fork at d4— but the square is protected by the knight at b3. So of course you look to take the knight and thus play RxN. The response a2xR follows, and after the exchange d4 has become a loose square. Black safely plays Bd4+, White’s king moves, and Black takes the rook. All this is familiar from our prior work on double attacks. But notice the different visual look of this position; see the White rook and king stretched out along the same diagonal, and realize that this signals a forking possibility. As discussed earlier, a rook often can make a good target for a bishop fork whether it is protected or not. Here, however, the fork worked only because the rook was unprotected. The reason, which is common, is that the fork required a sacrifice by Black in the

first place—here, a sacrifice of his rook for a knight. To justify that sacrifice, the fork that it creates has to make a big score. Taking a rook for nothing makes it worthwhile. Taking a rook that had protection, and then losing the bishop, would have made the combination a wash.

Dg222: What visual pattern do you see? Black’s king and knight on the same diagonal; this suggests that conditions may be right for a fork. Bd5+ almost does it, but the rook at d3 protects both the forking square and the targeted knight. White can’t capture the rook, so he proceeds by asking if he might capture the knight with some other piece, thus attracting the rook onto the knight’s square when it recaptures and leaving it loose. He can. 1. RxN, RxR both loosens the forking square and creates a loose target. Now Bd5+ forks and wins the rook.

2.3.4. Loosening the Target and Forking Square. Dg221: White to move Dg221: Almost the same. White has a check with his bishop in Bxd5. The move also attacks the loose rook at a2. The d5 pawn is protected by the knight at b6, but the knight can be captured with RxN, a7xR, leaving the forking square loose. White plays 2. Bxd5+, Kh8, and then 3. BxR. That is how the position comes apart under interrogation about its targets, but notice as well that visually it is almost identical to the previous one; the only difference is that a Black pawn lies between the king and rook. It is important not to let an obstruction like that prevent you from seeing that the king and rook are on the same diagonal. Look through the pawn as you trace the lines on the board with your eyes.

We now consider a common pattern that is a variation on the theme just considered. Often a possible bishop fork has a pair of problems: the piece it would target is protected, and the piece also guards the forking square. This most frequently happens when the target of the potential fork is a bishop or pawn. The solution then is to perform an exchange with one of your other pieces that trades the bishop or pawn for a better target—one that is loose and that cannot fire back at your own bishop when it executes the fork.

Dg223: White to move

Dg222: White to move

Dg223: An illustration will make the point clearer. Recall our current drill: look for any enemy pieces lined up on the same diagonal, and especially for pieces lined up on the same diagonal as the king. Here Black’s king and bishop are aligned. The bishop won’t work as a target for a bishop fork; it is protected and it

can attack the forking square. But seeing the geometry still can provide an idea to motivate your examination of forcing moves. A common way to deal with an unsuitable target is by capturing it with another piece, allowing a recapture, and then executing the fork against its replacement. So the solution here is the preliminary exchange RxB. If Black responds with RxR, now the bishop has been replaced with a rook that is loose and that cannot guard the forking square. Bc5+ wins back the rook and nets a bishop.

Dg225: Here is a position nearly the same as the previous ones, but involving a triangular pattern rather than a single diagonal. Still, ask the same questions; get comparable answers. Black plays 1. …RxB, 2. RxR, Bxf4+, forking Black's king and rook and netting a piece and a pawn.

Dg226: White to move

Dg224: White to move Dg224: The initial visual clue here is about the same as in the previous problem; see it, or simply ask what checks White’s bishop has. There is Bg6, attacking nothing else, and Bc6, attacking the bishop at b7—an unsuitable target that also guards the forking square. So again White exchanges the unsuitable target for a suitable one by capturing it and inviting recapture by Black: 1. RxB, NxR, and the bishop has been replaced by a knight that is loose and that cannot defend c6. Now 2. Bc6+ picks up the knight, winning two pieces for a rook.

Dg226: The salient visual point is that Black’s king, bishop, and rook all are lined up on the same diagonal. There is work to do before this can be turned into an effective fork, but the idea that will motivate your inquiry is clear. Bxc5 attacks the Black rook and aims the bishop at the Black king. The Black bishop on e7 is the only obstacle to a winning fork: it guards the forking square and blocks the line to the king. As usual, the remedy is an exchange of the bishop for a better target. 1. RxB, KxR; 2. Bxc5+ forks king and rook and again wins a piece and a pawn.

Dg227: Black to move

Dg225: Black to move

Dg227: What checks does Black have with his bishop? BxN+. The move also attacks a pawn at b4, and a protected one at that; and the pawn guards the square anyway, along with the White rook. So there is nothing here

yet, but if you at least see this much you will have the idea in hand and can use standard techniques to build a little combination out of it. Black takes the pawn with another piece: 1. …Rxb4; and now if 2. RxR, Black plays BxN+ and wins back the rook with the gain of a piece and a pawn. (In the actual game White replied 2. Ra5, BxN+; 3. RxB; Rf4+ (another double attack, this time against White's king and f-pawn); 4. Ke3, Rxf5 and Black was two pawns ahead.)

2.3.5. Moving the King into Position, etc. As you no doubt are noticing, the tools required to create bishop forks are the same used to create many forks by the queen and some by the knight. Here, as in those other cases, there often may be a forking square that needs to be loosened; the techniques for loosening it—e.g., a preliminary capture of the piece that currently sits on the square, or of the guardian of it—are the same regardless of whether the goal is to put a bishop, queen, or knight on the square. It would be possible just to leave it at that, but for the sake of building pattern recognition skills it will be worthwhile to see at least a few examples of how these processes look in the context of double attacks by the bishop. And in any event the thought process is not quite the same. In this section we consider cases where the bishop has no way to give a check, but where with some work you can build a fork that involves an attack on the enemy king at one end. The crucial initial question is how you would realize there is an opportunity for such fork-building in the first place. If the bishop has no checks, what would cause you to try to create a fork involving one? The answer, of course, is that you look for any other pieces the bishop can threaten that would form good targets for a double attack; having found one, you then go to work to create a check at the other end. We saw that in the queen’s case this generally meant that you had to find or create a loose piece to attack, because a queen can’t afford to attack anything that is protected. One of the

pleasures of attacking with the bishop, however, is that its list of good targets is longer; thus these positions require you to start by considering carefully whether the bishop can threaten any loose pieces, or rooks, or queens. These problems may require you to keep developing some new habits. If you are not an experienced player you probably are accustomed to asking what pieces your bishop (or your other pieces) can capture on the next move, but not what pieces your bishop can threaten on the next move (and thus capture in two moves). But that is the important question here, as it often was in the earlier chapters. In the bishop’s case the examination of possible threats is pretty easy because the movements the piece makes are limited and easy to follow. It also simplifies the task to remember that any possible targets of the bishop must sit on the same color square that it does. The visual patterns we used to set the analytical process in motion in the last section may be a little less helpful here, because at the beginning of these positions the king and the target piece tend not to be on the same diagonal or triangle. You still may be able to see that the king almost is aligned with another piece, and so have the idea of moving them into alignment with each other. Even if you don’t see that, the key patterns emerge here after an initial exchange or two; and much the point of mastering the relevant visual patterns is to be able to recognize them not just at the beginning of a position but as they emerge after you have imagined initial forcing moves and responses in your mind’s eye.

Dg228: White to move

Turning to the position on Dg228: What Black pieces can White’s bishop attack? (We do not just ask what Black pieces are loose, because a more valuable enemy piece may be a good target for a bishop even if it is protected.) Answer: it can attack the rook by moving to d2 or d4. Threatening a rook is a nice start, but becomes really interesting only if it also is accompanied by another threat in a different direction—i.e., if it is part of a fork. So what other threat can be engineered into existence? Bd4 aims the bishop in the king’s general direction; if the king could be moved onto the same diagonal as the rook, White would have a double attack. What checks does White have that force the king to move? Only one: f4-f5+. Carefully consider Black’s options in response. He can move the king to e5 or f6; there is nothing else. Either move puts the king into the path of the White bishop once it moves to d4+; and after the king then moves again, BxR takes the rook. Black can recapture with his other rook, but White wins the exchange.

Dg229: White to move Dg229: What Black pieces can White’s bishops attack? (Not what can they capture, but what can they threaten by moving.) Bf5 attacks the rook at e4. (The other rook is loose, but the dark-squared bishop can’t reach any squares from which to attack it.) The lightsquared bishop would have a fork if Black’s king somehow could be moved onto g6. The simplest way to move the king is with checks, and White has two. The first is Rf5, but this will not necessarily achieve the desired end (Black can play Kh6 or Kg6; Kg6 sets up a fork, but White can’t pull the trigger because his own rook is then on the square that his bishop needs). White’s other check is Bc1+—

another study in the importance of remembering backward moves. Black would have to either move the king to g6, thus walking into the fork Bf5+ and losing the rook; or he could try his only interposition: Re3, blocking the check. But then White plays BxR and wins the exchange. So 1. Bc1+ wins regardless. White starts out ahead in that he has two pieces for Black’s rook; after winning the exchange he is ahead by a whole piece.

Dg230: White to move Dg230: What pieces can White’s bishop threaten? Bxd5 attacks the rook on a8 and aims the bishop at Black's king. Or a visual way to assess the position is that it is a classic example of a king-and-rook triangle that lends itself to a fork at d5. Either way you look at it, the trouble is that the pawn on e6 blocks the way to the king and guards d5 as well. The point is clear: the pawn must be vacated from that square. Moving an enemy pawn off a square is best done by capturing something it protects. Here it protects the knight at f5; so 1. RxN, 2. e6xR does the trick. Now Bxd5+ safely attacks king and rook, picking up the latter next move and netting a piece.

Dg231: White to move

Dg231: White’s bishop can’t give a check and can’t safely threaten anything. But it can make a capture: Bxd5. Don’t just reason that it loses a piece to BxB; look for patterns that might form the basis of a tactical idea. On d5 the bishop would be aimed at Black’s king and rook, though its path to each piece is blocked. Again, a visual way to see the tactical possibility is to note the classic king-androok triangle that would lend itself to a fork at d5 if only the white rook and black bishop could be cleared out of the way. Pick either obstacle and think about how to get rid of it. If you start with the rook at b7, you need it to vacate its square in a violent fashion that requires a response and gives the enemy no time to regroup. The obvious solution is a capture: RxB, to which Black replies KxR, which takes care of both problems. Now Bxd5+ wins the rook. Or start your thinking with the Black bishop at f7. The natural way to get rid of it is by capturing it; and the only way to do so is with RxB, which again leads to KxR and the bishop fork from d5.

Black king somehow could be moved onto the diagonal leading away from the rook toward d8. The next step is to experiment with whatever (other) checks White has available.

Dg232: White to move

Dg233: White to move

Dg232: This one is a step up in difficulty. What can White’s bishop do? Its checks don't seem to lead anywhere, but there are other attacking possibilities to consider as well: Bg5, attacking the Black bishop (barely worth noticing because it's a useless target); Bd2, attacking the Black rook; and Bxb6, attacking rook and bishop. This last move has the appealing look of a double attack, but again the bishop is an unsuitable target. This may be as far as you can go with initial reconnaissance; what you know is that (a) White has no double attack as yet; (b) if he is to make one, the most plausible place for it probably would be b6; and (c) a fork there might be doable if the

Dg233: What can White attack with his bishop? Be4 attacks a knight, which might make a good start for a double attack if the knight were loose; but it is protected by the rook at d8. Nor would the bishop then be attacking anything else. Still, the sight of the bishop attacking an enemy piece while also aimed at h7 should stimulate your imagination. If a loose piece could be substituted for the knight, and if the king could be pushed onto h7 as it was in some earlier problems, White would have a fork. So experiment a little with those possibilities.

The only check White can give with another piece is Rd1+. How would Black respond? If he plays Ke6, White would be able to play RxB; the Black bishop would be the victim of a skewer. To avoid this fate Black would need to move the king not to e6 but to a square where it can protect the bishop: either Kc7 or Ke7. Then what? Again, the pattern that would then exist probably would be easy enough to recognize if you encountered it as an initial matter: With Bxb6 White has a double attack against the a5 rook and against either the bishop on d8 (if Black moved his king to e7) or against the king itself (if it was moved to c7). The fork still isn't quite there; White needs to perfect it by substituting the Black king for the Black bishop with RxB, to which Black responds KxR. Now Bxb6 at last wins the rook.

When a target is protected, one way to loosen it is to take it with another piece and allow for a recapture; here, 1. NxN, RxN and White has half of a bishop fork in place. Next White turns to any checks that would force the king onto h7 and finds Ra8 (remember that the Black rook no longer would be on d8). After 2. Ra8+, Kh7, White plays 3. Be4+ and wins the rook. This is a position we already saw early in the chapter, where it was advanced to its last step; the point of repeating it here is to enable you to see what the same fork looks like a couple of moves away. Notice, too, that the sequence succeeds here only in the move order described; trying to move the king first, and then performing the exchange of knight for rook, would not have worked. So remember to look for your checks before and after you imagine captures you can make. Dg234: What can Black’s bishop threaten? The two White pieces on light squares: the rook and knight, but not at the same time (the possible attacking moves are Be6, Be4, and Bxc2).

winning the rook without any need to force White’s king into a more vulnerable position. The lesson is to take notice if a bishop can attack both an enemy piece and a square next to the king. It may be that a preliminary exchange will allow you to move the king and so then check with the bishop move, or that aiming the bishop at that square will itself produce a mating threat that works just as well as a check as an anchor for the fork.

2.3.6. Bishop Forks of the King and Queen. When your bishop makes the queen the target of a double attack, you can't generally count on a fork or other nifty maneuver to save the day when your opponent replies QxB. So typically a fork against the queen only works if the bishop has protection. Here are a few examples of how this looks. Dg235: In the position on the diagram, White looks at his checks and sees that Qd8 forces Black's king to h7. He looks for his next check and finds Bf5, which forks Black's king and queen—but fails because Black simply plays QxB; by then, White's queen no longer is on the fifth rank to supply protection.

Dg234: Black to move Attacking the rook with Be4 has the interesting result of also attacking a square—h1— next to White’s king. In the previous problem this was exploited by forcing the enemy king onto the targeted square with a check. Here there is a different possibility. Consider the White king and the constraints on its movements. The back rank is owned by Black’s rook. If the bishop were attacking h1, Rh1 would be mate. So no setup is needed. Be4 threatens the rook and threatens Rh1#, thus

Dg235: White to move The fork would work fine if only the bishop had a guard. Ah, but White can have it both ways by giving the check with a different piece: Rb8. This likewise forces Black’s king and queen onto the same diagonal, and this time White wins with Bf5+.

Notice that the problem starts with Black threatening checkmate by playing Qxg2. In the face of this threat it would be natural for White to think defensively, but as we know, sometimes the best defense is a good offense.

amounts to nothing yet because the bishop wouldn’t be protected against QxB and because it has nothing else to attack at the same time. But the king is not far away, and if it could be moved onto h1 Black would have a classic triangular fork with BxN. Consider any checks Black can give and how they might change the board. There's Bb6xf2, which loses the piece, and then the more interesting Qxg3+. Can White reply f2xQ? No, because the f2 pawn is pinned. White therefore would have to play Kh1. Now BxN attacks both king and queen—and thanks to the previous move by the queen, the bishop now would have protection at f3. So White responds to BxN with QxB, and Black replies with QxQ+.

Dg236: White to move Dg236: We start with an open diagonal to Black's king, and a Black piece — the bishop — on the same line. Now look for checks White can give with his own bishop, and find Be5+. If the Black bishop could be swapped out for a better target, White would have a nice double attack. So capture Black's bishop with another piece: 1. RxB, QxR and now the scene is set for Be5+, forking Black’s king and queen. The point of seeing the position here is that since the queen is the target, White’s bishop needs protection on the forking square; it gets it from the f4 pawn. One of the many nice things about having a pawn in or near the center is that it can provide a protective anchor for a piece delivering a fork.

And what then? White has to move his king to h2. (Moving it to g1 is also a possibility, but eventually leads to mate for Black.) Black keeps the offensive pressure on with Bxf2. White has no appetizing options in reply. Black threatens to mate with Qg3+ followed by Qxh3#; White can prevent this by using his rook to take the bishop on f2 or by playing Rg1, but either way he loses the exchange. Seeing the initial forking idea here was the key point, but playing through the rest of the sequence in your mind’s eye will be a useful exercise in extending your range of vision. In summary, then, here is the most likely sequence: 1 …Qxg3+; 2. Kh1, Bxf3+; 3. QxB, QxQ+; 4. Kh2, Bxf2; 5. Rg1, Bxg1+; 6. RxB.

Dg237: Black to move

Dg238: White to move

Dg237: This time Black has no bishop checks (except the useless Bxf2+), so just ask what else his bishops can attack. You see then that BxN threatens White’s queen. The threat

Dg238: What checks does White’s bishop have? Bxe6. Does the move attack anything else? Yes, the bishop at d7, which is an un-

suitable target. Or see it visually: we have a classic triangle between Black’s king, queen, and e6 pawn; the bishop can be understood as an inadequate target or as an obstruction. Either way, the natural next step for White is to capture the bishop with another piece — as with RxB. Then if Black recaptures with QxR the board is prepared for Bxe6, now with Black’s queen as the target. Like the bishop that it replaced, the queen is a problematic target because it can fight back against the forking piece; but unlike the bishop, the queen’s value is enormous. So the fork works as long as White’s bishop has protection when it delivers the fork. It does; it will be guarded by the White queen. Play therefore goes 1. RxB, QxR; 2. Bxe6+, QxB; 3. QxQ+, and now White has won a queen, a bishop, and a pawn in return for a rook and a bishop.

by taking whatever the pawn protects and pursuing the consequences. Again, trains of thought like this will be the focus of our later study of pins.)

Dg239: A quick look at checks White can give with his bishop turns up Bxd6. Does the move attack anything else? Yes, the knight at e5. The knight is protected by Black’s queen (though also attacked once already by White’s knight on d3), which also protects the d6 pawn.

Dg240: Black to move

Dg239: White to move So play with exchanges White can initiate and with the move orders made possible by the threat White already has against e5. A natural possibility to consider is 1. NxN, QxN. This upgrades the target of the fork; it also leaves behind an open line of protection from the White queen to the forking square. Thus Bxd6 now forks king and queen. (Another way to see the idea here is to notice that the Black pawn on d6 is pinned to its king by the bishop at a3, and to look for ways to exploit the pin

2.3.7. Bishop Forks of Other Pieces.

Dg240: What checks can Black’s bishop inflict? None, of course, not least because the bishop is on a light square and the king is on a dark one. But the king is just the best anchor for a fork, not the only one; you really are looking for a square where your bishop might be able to attack any two vulnerabilities at the same time. Here the bishop can move to c6 and attack White’s b7 knight and h1 rook, both of which are on the same light-squared diagonal and both of which are loose. Black wins the knight. If you step back from the board and look for visual patterns, the alignment of White's knight and rook with nothing between them should be conspicuous. Use these studies to gain the habit of spotting enemy pieces like these that are on the same line (not to mention loose). Dg241: Black has no bishop checks (Bc5 obviously would be unsafe, but it's irrelevant because the bishop is pinned). Think more broadly about threats he might make with the piece. White’s bishop, knight, rook, and queen all are on light squares, and so is Black’s e4 bishop. The queen and rook are on a common diagonal and so can be attacked with Bc6. When a bishop forks the enemy

queen it requires protection, as we know; it has the needed cover here from its own queen at c1.

Dg241: Black to move Black thus wins the exchange: 1. …Bc6; 2. RxBf8+, RxR. Or perhaps he wins a queen for a rook and a bishop, the result if play goes as follows: 1. …Bc6; 2. QxB, QxQ; 3. RxR, Kg7 (protecting the bishop). (Or instead 2. RxR, BxQ; 3. RxB+—same basic result.) Dg242: Black is confronted with a fork by White’s bishop; he is about to lose the exchange to BxRf8. But instead of reaching to move the knight, think about Black's own offensive options.

Dg242: Black to move Again he has no checks, but ask anyway what else his pieces can threaten. In this case his dark-squared bishop can fork the White pieces also on dark squares: the knight and bishop. (Step back and scan the diagonals and other lines for pieces lined up on them.) The knight is loose, but of course the bishop is protected and anyway is an unsuitable target for a bishop fork. We handle this in the usual way: Black takes the bishop with RxB, to

which White replies RxR. Now Be5 picks up the knight next move, netting two minor pieces for a rook. Or perhaps things play out differently (the following sequence will take a bit of patience to follow): White can reply to 2. ...Be5 by leaving his rook on d6 and instead playing Nf5, taking his knight out of the fork and using it to give the rook protection. If Black replies e6xN, notice that White now has the rook fork Rd5—attacking the loose Black pieces that would then be on c5 (the knight) and e5 (the bishop). The pawn on e6 was guarding against this danger before it captured (in this variation) on f5. So instead of e6xN Black would want to respond to Nf5 with RxN. Now White has the recapture e4xR, but then Black has BxRd6, with the fork at last paying off. He ends up with two minor pieces against Black’s rook. Now for extra credit, do you realize that the success of Black's fork here depends on his knight at c5 and his pawns on b7 and e6? Let's consider why. First, once White is forked he almost can move his rook both out of harm’s way and into position to protect his knight by playing Rd3. If this move were feasible the fork would be foiled; it is not feasible only because d3 is attacked by Black’s knight. This pattern nevertheless illustrates once again the extra difficulties created by double attacks against two ordinary pieces rather than the king: you have to ask what mischief either of them could make in breaking out of the fork. And then notice, too, that the aforementioned Black knight on c5 is loose. This makes it a vulnerable target, so you need to worry that White might break out of the fork and make a counterattack against the knight. This almost is possible; once White’s rook is baited onto d6, it nearly can break out of Black's subsequent bishop fork with Rc6 or Rd5, threatening the knight. But not quite, because both of those squares are guarded by Black pawns. The lesson: we know that when you fork two enemy pieces (not the king), you need to ask whether one of those pieces might spoil the fork by rushing to the defense of the other;

but consider as well whether one of the pieces in the fork might go off and make a threat against you elsewhere.

Dg244: Black to move

Dg243: White to move Dg243: White has a bishop check with Bd6+. How would Black respond? Probably with Ka8. Whenever you imagine a move that would force your opponent to move—and especially a move that would force him to move his king—imagine the position that would result and interrogate it with the same questions you might ask if it were the board in front of you. What Black pieces would be loose? What pieces are aligned? Black's queen and rook—which indeed are already aligned from the start, and would then be forkable with Bc7. Since the queen is one of the targets, naturally we look to make sure the bishop will have protection. It will, from the rook at c4. This description suggests how looking at every check might have led to the fork. Another way to see it, though, is to step back and notice first Black’s queen and rook on the same diagonal, especially since they have no pieces between them. That pattern is a set up for a double attack by the bishop. The question then becomes whether you might maneuver the bishop into position, since it cannot get to c7 directly. When you want to make a preliminary move without giving your opponent time to defend against the fork you are creating, the preliminary move has to be forcing. A check is best. Conveniently, White’s bishop can give a check on the way to c7 by stopping first at d6.

Dg244: The queenside cluster of White’s pieces looks knotty, but there is nothing difficult about it if you ask the right questions. We are focusing on attacking ideas with bishops, and for Black there is just one: BxN, forking White’s bishop and queen—a small triangle. Of course the White bishop first needs to be traded in for a better target through capture by another Black piece; hence 1…. RxB; 2. RxR and now BxN forks White’s rook and queen. Targeting the White queen works because Black has protection from its own queen at c4. Are you satisfied with this? You should not be. Remember that when you fork two pieces that aren’t the king, one of them can move to protect the other. So think especially carefully about what your opponent’s best move will be in reply. Here White can respond to the fork with Qc1, protecting the rook. The sequence still would be profitable since Black would have picked up the knight on c3, but keep pushing for ways to go farther; after White’s queen moves to c1, rethink the board. White’s rook is attacked once and defended once. If Black could add his queen to the attack against the rook then on b2, he would have it. He needs a way to do that without giving White time to move the rook out of danger. He therefore maneuvers the queen into position with a time-consuming (for White) check: Qd4+. (This is safe because we're assuming that White's queen has moved to c1.) White has to move his king; and now BxR wins the rook at no cost because Black’s queen protects against a recapture. (White’s better option after the forking move BxN is to play Qxd6, at least taking a pawn rather than making futile efforts to save his rook.)

Incidentally, at the outset of the position Black might be tempted to play BxN; once White recaptures on c3 with his bishop, the way is clear for Black to take White’s loose rook on b1 with RxR+. But the idea fails because that recapture by White—BxBc3—is a check. You cannot be too alert to possible checks your opponent can give in the midst of a plan you are devising. A check has the power to stop a tactical sequence in its tracks. Dg246: White to move

Dg245: White to move Dg245: This time start by looking for pairs of Black pieces that might be vulnerable to a bishop fork. How? Look for pieces on squares of the same color, or on the same or intersecting diagonals. The c5 knight and e7 bishop are in the right pattern, but there is no way to exchange the bishop for a suitable target. But now what about the pieces on light squares? Black’s rooks are on a6 and a8—on the same file, one square apart, and arranged for a bishop fork with Bxb7. White’s light-squared bishop is aimed the right way; the only trouble is that White’s own pawn is in the way at d5. If it is going to move, first the Black pawn in front it has to be moved. You move a pawn by capturing something it protects; here it protects the knight at c5, so 1. NxN (capture with the least valuable piece you can), leading to 1. …d6xN, clears Black’s d-pawn onto the c-file. Now White moves his own pawn forward to d6, making a threat against Black’s bishop that requires a time-consuming response. After the bishop moves (presumably with Bxd6), White is able to play Bxb7, forking both Black rooks and winning the exchange next move.

Dg246: A position like this is best approached visually. What do you see? Both of Black’s knights, his rook, and a pawn are lined up on the same light-squared diagonal. White’s light-squared bishop can, in principle, intervene at c6. Nothing can be done with this yet, because pieces are in the way, squares and pieces are guarded, etc. The point is just to see the idea. Then you can play with exchanges, carefully visualizing their consequences to see if they help clear the obstructions out of the way and improve the targets. White has two possible captures that might help the b5 bishop to make trouble: NxNc6 and NxNe4. In effect those possible captures are options you hold to make the board look different. If you play NxNe4, Black will play RxN, and now the board will be changed; likewise if you then play NxNc6 and Black replies b7xN. (He can’t play d7xN because after White moved his d4 knight, Black’s dpawn became pinned to his queen. Black’s rook no longer will be protecting the queen, either, having moved to e4 to recapture during the first sequence.) Notice how two exchanges White can initiate so change the look of the board even if they don’t turn any profits themselves. And then what would be possible? If the position were set in front of you the answer would be obvious: Bxc6, forking the rooks and winning the exchange. (Black plays RxBe3, and White recaptures RxR.) Lesson: move order matters. There are a number of ways to look at White’s captures in the wrong order here and find nothing; capture

with the wrong knight first and the sequence is ruined.

2.3.8. Playing Defective Bishop Forks. We conclude with a series of positions where a potential bishop fork looks unplayable because the forking square is guarded—but where the fork nevertheless is the winning move because checkmate or some other decisive consequence results if the forking piece is taken. We have seen that a parallel logic can make seemingly bad knight forks quite productive; naturally the same is true of any other sort of fork that may not look feasible at first. Dg247: A first example of the idea. Look for a visual pattern; see that White has his king, rook, and d4 pawn arranged in a classic triangle that calls for consideration of a queen or (here) bishop fork by Black. (You could also just ask what checks Black’s bishop has; the only answer is Bxd4.) Bxd4+ thus has the potential to take the rook at a1, but the d4 pawn is protected by White’s knight.

Dg248: Black to move Dg248: Think visually. White’s king and a6 rook are on the same diagonal, inviting Bc4+. Or again you could see this by asking what checks Black can give with his bishop and seeing that one of them—Bc4—also attacks a rook. Either way the problem is that White protects c4 with his other rook. There is no immediate way to get rid of the rook, but before moving on ask what happens if Black goes through with the fork and White plays RxB. What checks could Black then play? Rb8-b1, which is checkmate (after White uselessly interposes his rook from c4 to c1). So Bc4+ wins a rook despite the apparent protection of c4 by White’s rook, which really can’t afford to move. The tipoff here is Black’s other rook on the second rank; it traps White’s king on the first rank, making it vulnerable to a back-rank mate if the rook on c1 leaves its post.

Dg247: Black to move There's no good way to get rid of the knight, but don't stop there. Imagine the sequence failing and ask what it would make possible. It then goes 1. …Bxd4+, 2. NxB. What lines would then be open? What checks would Black then have? The answer is Qe1—mate. So the bi-shop fork at d4 works after all, winning a rook and a pawn.

Dg249: White to move Dg249: Whether you look for Black pieces on common diagonals or ask whether White has a way to attack two pieces at once, the same answer appears: Bd7. The move seems pointless because Black just plays QxB. But ask what checks White then would have. There

are four: Qe8, Qe7, and Qb4, none of which are new and none of which works; and QxR, which is new (well, the move itself isn't new, but it didn't give check in the initial position), and which leads to checkmate a move later. (If Black blocks the check with Qe8, White has QxQ# with protection from the rook on e1.) Since Black can’t afford that, the initial fork Bd7 actually works well, picking up the knight. The key to seeing this, as ever, is to be thorough in examining checks and their consequences—not only on the board in front of you but on the board as it would look after whatever forcing moves you can imagine. You likewise want to be alert to how any recaptures you can force would open lines or leave things loose. Here the Black queen’s movement off the back rank opens a line to the king from a8, and turns out to be fatal. It is good to see the bishop fork in this position, but there is another route to a similar result that is worth seeing as well. All sorts of possibilities spring up once you realize that Black’s queen needs to stay on the back rank to prevent White from mating with QxR; for this means the Black queen itself is vulnerable to attack. White therefore can play Bxa6, putting Black in a pickle. If he plays QxB, he promptly gets mated; so he moves his queen to e8, where it is safe and continues to protect the rook on a8—but now he has left his knight loose, so White plays QxN. Black’s queen was overworked, a theme we have seen before and will study in detail later. There is more than one way to take advantage of such a situation, as this analysis shows.

Dg250: White to move

Dg250: You can see the idea here visually by noting the dark-squared triangle between Black’s rook, king, and e-pawn, or by asking what checks White can give with his bishop and what else he can attack at the same time. Either way White would like to play Bxe5 but seemingly is prevented from doing so by the threat of NxB. Ah, but what if that threat is carried out? Lines would be opened by the moves of White’s bishop and Black’s knight. White would have a new check with Rc7 — a rook fork which also attacks Black’s queen. If Black moves his king or blocks the check by moving his knight or bishop to d7, White plays RxQ. If Black plays QxR, then White plays QxQ+, and then (after Black moves his king) QxR. Dg251: White’s rooks are arranged on the same diagonal and thus could be forked with Bxb2. But that won’t do because White is on the verge of mate with Qa8, Qxc7, or Ra8. Black’s next move therefore needs to be a check that forces White's reply. He has four. Two can be dismissed quickly: Rd1 just loses the rook and Qxg2 just loses the queen.

Dg251: Black to move A third check, Bxh2, is a little more interesting, as White wouldn't particularly want to reply KxB; for Black would then have the queen fork Qh6+, compelling White to trade queens to get out of it. Instead White would move his king to f1. Now Black has the queen fork Qxc1, again forking White's king and queen—but this time without protection. So White plays QxQ. Black has taken a pawn and a rook but has given up his queen for the sake of disrupting the mate threat. So all this is possible, and might even seem an appealing

reprieve from execution—but hold! For there is yet one more initial check for Black to consider. Starting with this last remaining check, QxR+, turns out to be most interesting of all. White replies QxQ, letting go of his mate threat. Now what would be possible? White’s queen and rook would be on the same diagonal, so Black toys again with Bxb2. Of course White could just play QxB. But again you consider what lines would have been opened by all this and what checks Black would then be able to inflict. As for open lines, Black’s bishop would have moved off of the e-file, creating a new path for the rook on e8; now the rook could move to e1—which would be mate! So in reply to the forking move White is obliged to move his queen and let his rook on a3 be taken by Black’s bishop. Black emerges with two rooks and a pawn in exchange for a queen—a slight material gain; and meanwhile he has obliterated White’s mating threat and reached a winning position. It's yet another study in the importance of examining every possible check, both on the current board and on the board as it would look after an exchange or two.

2.3.9. Strategic Implications. A bishop’s power—its potential to execute double attacks and its usefulness in other ways—generally depends on whether it has open lines on which to move. A bishop placed on one of the long diagonals with nothing in its way is a mighty force on the board; a bishop blocked by its own pawns has relatively little use. It might seem to follow from this that you should try to maneuver your bishops onto open diagonals, and indeed that generally is good practice. But there also are other, subtler steps you can take to increase the power of your bishops and limit the power of your opponent’s.

Dg252: Dg252: The first thing to understand is that at any given moment your two bishops may differ greatly in their attacking potential. One travels on the dark squares, the other on the light squares. Usually one of them turns out to be more useful than the other, because either the dark or light squares in the middle of the board—but not both—will be open. “Open,” here, means unoccupied by pawns. Notice that your pawns frequently are set up on squares of the same color; that is how they protect each other. If your pawns are arranged on light squares, those squares are “strong” for you and the dark squares are weak—i.e., unprotected by pawns. But it also means that your dark-squared bishop has room to run and that your light-squared bishop is likely to be less useful, at least until the pawn structure changes. Thus we speak of a bishop as “good” if it travels on squares unobstructed by your own pawns; a bishop is “bad” if it travels on the same colored squares your pawns do. In the skeletal diagram to the left, both bishops are fianchettoed (i.e., White has developed them to the squares in front of his knights’ original positions). The dark squares are very strong for White because he controls them so thoroughly with his pawns. But a side effect is that the bishop on b2, which travels on the dark squares, is bad; the bishop on g2 is good. We focus on the pawns near the center because the best diagonals pass through the middle of the board. If you look back at the studies in this chapter, you will see that the attacking bishop usually takes advantage of open paths through the center; it rarely is the case that there is a center pawn on the same colored square as the bishop that delivers the

fork. There may be an enemy pawn there that is captured by the bishop, but there generally is not an allied pawn that blocks the bishop’s way. Notice that even one pawn in the middle can be significant, since it single-handedly blocks long diagonals in two different directions. These points have several implications. First and most obviously, you should think of your two bishops as quite different pieces, and you should be much more willing to trade away a bad bishop than a good one. Second, pawns and bishops have an intimate relationship. Think of pawns as pylons that obstruct the paths of the bishops; every time you move a pawn you open one diagonal and block another, and this may be the most important consequence of such a move. Whether lines are open or closed will matter for your other pieces as well, of course, but all of the other pieces have the option of moving back and forth between light and dark squares if necessary. Bishops cannot, so they are especially sensitive to pawn placement; moving your bishop often does less to make it powerful than moving a pawn out of its way and onto a different colored square. If that can't be done, you need to maneuver your bishop outside the pawn structure. In any event, try regarding pawn moves as indirect bishop moves.

2.4. The Rook Fork.

2.4.1. Introduction. Double attacks with the rook are simple enough to understand, but they also are easily overlooked because the rook is used so heavily for other more familiar purposes. The suitable targets for a rook fork are the enemy king, the enemy queen (if the rook has protection), or any loose piece. As a practical matter the targets of a rook fork almost always include either the king, a loose piece, or both; this will be the guiding principle behind our target-based searching. The visual pattern involved also can be stated simply: a rook can slide between two pieces on the same rank or two pieces on the same file.

Dg253: Black to move This principle is important from a defensive standpoint as well. If you move a pawn and the move opens an important diagonal— especially a diagonal leading toward your king or another valuable piece—you immediately strengthen the enemy bishop that travels on that diagonal. Conversely, a pawn move or exchange can have a powerful effect on the enemy if it creates an obstacle—or, even better, gridlock—on the squares where his bishop wants to move. This is particularly significant if he only has one bishop left. Locking your pawns with his so that his bishop can’t get through the center will tend to make his bishop impotent for so long as the pawn structure remains in place.

Dg253: The first pattern is more common; in the skeletal diagram, White’s rook has forked Black’s king and bishop. The other type of fork—the double attack against pieces on the same file—occurs less often and can be a bit harder to see because the rook then moves horizontally. The eye is more accustomed to tracing the rook’s path up and down the board, rather than from side to side. Another factor sometimes making rook forks harder to see is that the enemy targets may begin with other pieces between them — yours, his, or both—that have to be cleared out of the way before the fork can work. The solution to all these difficulties is to be habitual and thorough in looking for enemy pieces on the same rank or file, just as you are in looking for pieces on the same diagonal—and

this regardless of whether there are other pieces between them. The principle is general: when you look at lines on the board and pieces resting on them, follow all the way through. Don’t let your eyes stop when they hit an obstacle, because the obstacle may be removable through an exchange or by other means; if there are two enemy pieces on the same line, you want to see that pattern every time regardless of what lies between them. Occasions for double attacks by a rook arise less often than forks with the other pieces we have considered, and there are only a few special wrinkles that rooks present. This chapter therefore is shorter than the previous ones.

Dg255: Black to move Yes, it picks up the loose bishop on b2. Anytime you see the enemy king and another piece other than a rook on the same rank, an instinct for a fork should be triggered.

2.4.2. Simple Cases.

Dg256: Black to move Dg254: White to move Dg254: Let's begin with some simple rook forks. Ask traditional questions: What Black pieces are loose? The knight and rook. What checks can White give with his rook? Rd1 and Rb7. We seek a match between these possibilities and find it in Rb7+, a move that wins the knight after Black moves his king. Absorb the position visually. The spectacle of the Black king and knight both on the penultimate rank should immediately suggest tactical possibilities. They aren’t on squares of the same color, so a double attack by a knight or bishop won’t work, but they are easy prey for a rook (or queen). Dg255: Start by asking what Black can do with his rook; the first part of the inquiry is whether it has any checks to give. There is one: Rc2+. Does the move attack anything else?

Dg256: What checks can Black give with his rooks? None. What loose pieces does White have? Two: the bishop and knight (as usual, we’re setting pawns to one side), and they are lying on the same rank—the second, perfect for a double attack by the rook. As this position and the previous one both show, rook (or queen) forks on the opponent’s second rank are a fairly common pattern because pieces there often are loose: they frequently get no protection from their fellow rooks, which are on the first rank, and they can’t be protected by pawns. Naturally this pattern lends itself to double attacks by the queen as well; the rook’s moves, like the bishop’s moves, are a subset of the moves a queen can make. In any event, Rd2 wins Black a piece. Dg257: White has no checks with his rook, but you want to be equally alert for attacks you can make against loose pieces. Here the

bishop at h5 is Black's only loose piece, and the rook can attack it with Rf5.

be a little harder that the other type to see at first, as noted earlier.

Dg257: White to move

Dg259: White to move

From that square you see the rook also can attack the knight at e5. The knight is protected by the Black queen—but it also is already attacked by the White queen. So the knight is a classic case of a piece that is threatened once and protected once and therefore is as good as loose. If Black moves the bishop after White plays Rf5, White then plays RxN and Black dares not recapture lest he lose his queen to QxQ. White wins a piece.

Dg259: The arrangement of Black’s king and knight seems almost perfect for a rook fork: a king and a loose piece on the same rank with nothing between them always should set off an alarm, and here White has a rook at the ready on e1. The problem is that the Black king guards the forking square, e7, and White has no way to add protection to that square that is safe and holds the initiative. Time to give up? No; time to imagine playing the fork anyway and asking what would be possible if it fails. Thus 1. Re7+, KxR; and now Black’s king has moved, requiring a fresh look at the resulting position. The king’s move would have left the bishop on g6 loose; plus the king would be on e7, a dark square; and the rook at h8 would be on a dark square as well. White has a knight in the vicinity, and on a dark square. You get the picture: 2. NxB+ is a knight fork that takes the bishop right away and wins back the rook next move. White gains a piece with the sequence.

Dg258: Scan for checks with Black’s rooks and you find two: Rh1 (losing the rook to KxR), and Rg3. Ask whether Rg3 attacks anything else, and find the White knight at g5, which is loose (so you would have been looking for a way to take it anyway). Does Rg3+ lose the rook to f2xR?

Dg258: Black to move No; the pawn is pinned by Black’s bishop at c5, so its protection of g3 is illusory. Rg3+ thus wins the knight. This is an example of a rook fork requiring a horizontal move; it may

This position illustrates a valuable instinct to develop. The mind recoils initially at the thought of Re7+ because it loses the rook; the natural temptation is to abandon the idea and search for something safer. Cultivate the opposite habit of mind: a willingness to persist, imagining the loss of the rook and looking for what would then be possible on the board. 2.4.3. Creating a Target. Now we turn to studies that involve creating targets for rook forks, usually by forcing a

preliminary exchange. A common complication is that at the outset of the position the rook’s path to the forking square is blocked by the piece that starts the exchange; you have to be able to see that the exchange not only creates a good target but also creates an open line for the rook to reach the key square.

first the e1 rook may look most promising, but in fact the one on a5 has the more intriguing potential. Follow its path horizontally through the White knight (at e5) to a square where the rook can give a check (g5). Again the question becomes whether the knight can vacate e5 in a way that creates a target on the other side of the check. 1. Nxg4 is the answer; if Black replies NxN, then Black’s knight ends up loose and 2. Rg5+ wins it after the king moves. This is almost identical to the previous position, of course, except that the rook’s move is horizontal rather than vertical.

Dg260: White to move Dg260: Begin with the position on the left. A customary way to start thinking about tactical opportunities is to ask what captures White can make and with what consequences. Here he has just one: Nxb7; the recapture is BxN. Obviously the exchange is unprofitable on its face, but imagine the board afterwards and ask what would then be possible. What loose pieces would Black have? Both bishops. What checks would White have? Re1 and Rc7, the latter as a result of the line opened by the earlier exchange. These facts can be stitched together into a fork: Rc7+ wins the bishop that would then be on b7.

Dg261: White to move Dg261: This time try tracing the White rook’s possible moves through any other pieces, searching for interesting destinations for it. At

Dg262: White to move Dg262: What checks can White’s rook give? Two: Rxf7 and Rd8. The interesting question about Rd8 is whether a Black piece can be moved elsewhere onto the back rank and thus turn that check into a double attack. White only has one other piece to work with—the bishop; so try attacking something with it. Bb5 threatens the Black knight and forces it to move. Where can it go? Its only safe square is b8—and once it’s there, Rd8 forks and wins it. At several points in our studies we will see this principle used: an attack on an enemy knight that forces it to move somewhere useful to you. The thing to remember about knights is that their range of motion is inherently limited; they never can make it to more than eight squares, and where (as here) they are near the edge of the board that number gets even smaller. This often makes it easy to figure out where a knight will have to go if attacked, and thus turns attacks on enemy knights into very useful forcing moves.

Dg263: White to move Dg263: What Black pieces are loose? Really just the bishop on d1; notice how Black’s knight is protected by the Black rook against capture by White’s rook. How can White attack the bishop? With Rd3. To make that move interesting, another loose piece needs to be lured elsewhere onto the d file. The Black knight is the only real candidate. Ask what the knight protects on the d file that you might attack. Seemingly nothing—but maybe you can get the knight onto the d6 square by making trouble there with a pawn advance toward promotion (and the two exchanges that naturally follow): 1. d5-d6, c7xd6; 2. c5xd6, Nxd6; and now 3. Rd3 forks the bishop and knight. Black might see this and postpone Nxd6, first playing RxR; Black is thinking that after White recaptures with f2xR, Black can play Nxd6 without fear of being forked. But White doesn’t reply to RxR by recapturing. He moves his d-pawn to d7 and now it can’t be stopped from promoting. Black is better off putting up with the fork after all. 2.4.4. Moving the King into Position.

Dg264: White to move

Dg264: What interesting visual pattern do you see here? Black pieces lined up on the seventh rank. The White rook on e1 is poised to attack at e7, but Black's queen prevents this and isn’t a feasible target anyway since it can bite. Still, the idea suggested by the arrangement of Black’s pieces is the important thing because it guides your thought experiments: now you have in mind an attack with the rook and can look for exchanges or other forcing moves that might make it possible, particularly by replacing the queen with a better target. White has a capture (and check) available for the purpose: QxQ+, to which Black replies KxQ. Now comes White's Re7+, forking and winning the now-loose bishop on f7.

Dg265: Black to move Dg265: Again, start with the visual pattern, this time from Black's point of view: White has two pieces — the two bishops — on the same rank. The one on a3 is loose. The arrangement suggests a possible fork by the rook. Of course Black’s own knight is in the way at d4, and would need to be vacated with a threat that forces White’s response; and the other White bishop—the one at f3—is not yet loose. But both problems can be addressed with an exchange. Black plays NxB; White replies KxN. In addition to bringing the king onto the same rank as the loose bishop, the exchange opened the d-file for Black’s rook. Now Rd3+ wins the piece. A general point: When you have a chance to exchange minor pieces, as Black did here, as a matter of course you should play through the exchange in your mind’s eye to see how it leaves the board—what lines it opens, what becomes loose, etc.

Dg266: White to move

Dg267: White to move

Dg266: What Black pieces are loose? The knight and rook. Focus on the knight, since it makes a good target for an attack by your own rook. White’s rook can attack the knight in one move (either Rc3 or Rd6). If only the Black king could be pushed onto the same rank or file as the knight; but how? White’s bishop is no help because the king is on the wrong color square. But White has pawns near Black’s king, and pawns are perfect for pushing pieces around by threatening them. Put more simply, what checks does White have? Answer: push a pawn to f4 or h4. Either way the only legal move for Black’s king is onto the sixth rank. When the enemy king is forced to move, you reevaluate what would be possible—what new checks. Answer: Rd6+, winning the knight.

Here White has Rxg6+, which goes nowhere; but then he also has Qd2+ (don’t overlook backward moves!). Black is forced to move his king onto the same rank as his queen. Rd7+ forks them, and a move later Black wins a queen for a rook. Notice that attacks by the rook against a queen, like similar attacks by a bishop, only work if the attacking piece has protection; here White’s queen still guards the eventual forking square (d7) when it delivers check from d2.

So that’s the forking idea. But actually White has something even stronger. 1. Rd6 threatens to mate next move with h3-h4. Blocking the idea with h5-h4 doesn’t work for Black, because then White has f3-f4+ (forcing the king to h5) and then Bd1#. Instead Black has to reply to 1. Rd6 with Rxa4, using his rook to defend the fourth rank. But then White has BxR and the threat of f3-f4#. Black can fend off the immediate mate threat with f5-f4, but promptly loses his knight to RxN—and now he is out of pieces. The sequence is worth playing through in your mind's eye a few times.

Dg267: Avoid doing anything without first examining any checks you can give and their consequences.

Dg268: White to move Dg268: Near the beginning of the James Bond movie From Russia with Love, a chess match is depicted between the villainous Kronsteen, playing the White pieces, and one McAdams. The position is pictured here. Kronsteen plays 1. NxB, discovering check. McAdams replies Kh7. Meanwhile Kronsteen has been summoned away by a secret message from his bosses at SPECTRE; so now he plays 2. Qe4+—and McAdams resigns. Black’s best reply move would have been 2. …g7-g6, blocking the check, but this creates a fork for White with Rf7, winning Black’s queen for a rook. The position was based on one that arose between Boris Spassky and David

Bronstein in Leningrad in 1960, though in the real game there were White pawns on c5 and d4. Bronstein resigned after Spassky played 2. Qe4+. As a study in the rook fork the lesson of the position lies in three events that make Rf7+ possible: (a) Black’s king stepped forward from the eighth rank to the seventh, a classic site for rook forks because the rank can't be guarded by pawns and tends not to be patrolled (for defensive purposes) by rooks. (b) One of Black's pawns stepped forward from the seventh rank to the sixth, opening a line between the king and queen. And (c) White’s Qe4 cleared a path up the f-file for his rook. Each of these events is a type that can cause new tactics to become available: pins and skewers, as we shall see later, and forks, as we see here. That’s all you need to see about the position for present purposes, but for the sake of completeness we can consider a couple of other variations. What, for example, is Black’s best reply to White’s initial 1. NxB? It’s 1. …Ne6, which blocks the check and pretty well puts out the tactical fire. Suppose, however, that in reply to 1. NxB Black plays 1. …Kh8. Now White can’t play Qe4 with check to clear the way for the rook fork. But White still has a wonderful move: Qc4, aligning the queen with the bishop on b3 and threatening to mate next move on g8. Black has no good reply. Kh7 doesn’t help at all. Qe6 blocks White’s queen but now allows White to play RxN+ instead. If Black recaptures RxR, his queen is left loose and White takes it. If Black doesn’t take the rook he soon will be mated. So Black’s best move after 1. NxB+, Kh8; 2. Qc4 is Nd7, clearing a path for the e8 rook to use to protect the mating square g8. But the knight’s move leaves g6 loose, and White uses it to play Ng6+, a fork that takes Black’s queen next turn. Finally, suppose that after 1. NxB, Kh7; 2. Qe4+, Black declines to step his g-pawn forward and instead plays 2. …Ng6. This blocks the check without opening up the seventh rank for the rook fork White would like to play. But now Black is in bigger trouble, as

White has 3. QxNg6, Kh8 (forced); 4. Nf7+ (always look for the next check in these situations). Now if 4. …Kg8, then 5. Ng5+ (discovering check by the bishop), and White is about to mate. Or if 4. …QxN, then 5. RxQ and White again will mate soon; Black can use his rook to throw some checks at White’s king, but this is just desperation. Other replies to White's 2. Qe4+ likewise end with Black getting mated. E.g., 2. …Kh8; 3. Rxf8+, RxR; 4. Ng6+, Kh7; 5. NxR++, Kh8; Qh7#. Some of the ideas in these variations—as well as the idea of the discovered check that starts the sequence when White's knight steps away from f7—will be easier to understand after you have worked through the later parts of these lessons. 2.4.5. Clearing Paths. In the following positions there is a rook fork waiting to happen: two enemy pieces on the same rank or file, one of them loose, or one of them the king, or both. But there are pieces between them, or between the rook and the forking square, that have to be gotten out of the way for the double attack to work. Again it is important to recognize the basic visual patterns involved—enemy pieces on the same rank or file, suggestive of a fork—without being thrown off by obstructing pieces that you might be able to remove. Look for visual patterns on the diagram. Dg269: We see a familiar layout of Black pieces, with the king and a loose knight — prime targets for a fork—on the seventh rank.

Dg269: White to move

If White could get a rook between them, the knight would be his. The Black pawn at e6 is the only thing in the way. The natural method for getting a pawn out of the way is to take something it protects. Here it protects the pawn on d5, so White takes it with Bxd5. If Black replies e6xB, now Re7+ forks king and knight. The net gain is a pawn.

attack with White’s rook: a king and loose bishop on the same rank with nothing between them. Can the Black rook be attacked?

Dg271: White to move

Dg270: White to move Dg270: White has no checks that are immediately productive (though Ne7+ is not bad), so he looks for any Black pieces that might be loose. There is one: the bishop on h6. He has no direct way to attack it, but since a loose enemy piece is a big opportunity White considers whether he might build a double attack against it. Look for a visual pattern: the bishop is on the same rank as the Black queen. If the pieces between them could be cleared out of the way, White would have a fork with Rc6; the rook would be protected from QxR by the pawn on d5. Of the two men in the way, White can control its own—the knight at c6. Where can it move, and with what results? The only capture it can make is NxN. Black would reply d6xN; the pawn gets pulled off the sixth rank. Now the way is clear for Rc6, forking bishop and queen and thus winning a piece. The initial capturing sequence here illustrates a pattern of general interest: when two pieces need to be cleared off of a path, sometimes moving one of them also can force away the other. Dg271: Look for a pattern; look for enemy pieces arranged on the same line. Black’s king, rook, and bishop are spread along the back rank. If the rook were out of the way there would be a classic setup for a double

No. Can White attack something the rook protects? What does it protect? The knight on e4. So White takes the knight with NxN, Black responds with RxN, and now with the Black rook out of the way White plays Rd8+ and wins the bishop. That would be one way to see the position; another would be to begin by experimenting with captures. White sees that he can play NxN. Automatically he imagines it and considers what it would do to the board. It would cause Black to play RxN. Then what would be possible—especially what checks? Answer: the fork Rd8+. When the queens are faced off against each other like this, exchanging them is an option both sides have to consider at every turn. A capture by either player will require an immediate recapture, which may open lines, leave loose pieces elsewhere, etc.

Dg272: White to move Dg272: Here White imagines QxQ and Black’s compulsory recapture NxQ. This

simple sequence leaves behind loose Black pieces on c5 and f5 (whereas there were no loose Black pieces before), and a clear path for White’s rook from e1 to e5 (whereas there were two pieces in its way at the outset). Now the rook fork Re5 wins a piece. This position is a good illustration of how a single exchange can radically alter the tactical opportunities on the board. The solution is easy enough to spot if you understand the significance of loose pieces—and probably impossible if you don't.

the b2 bishop, which would have been left loose by the exchanges that started the sequence. The rook fork Rd2+ then wins the bishop next move. The prospect of a rook fork is nowhere in sight at the outset of this position. You would see it only by patiently imagining the exhaustion of exchanges on c4, then your next check, then the resulting pattern with the king and loose bishop on the same line. If the latter position were set in front of you its solution would be clear. It is worth studying this position until its solution is equally clear because you are able to visualize the consequences of those initial moves. Notice that it involves several of our major themes in constructing forks: creating a loose target, loosening the forking square, and moving the enemy king onto a square where it can be forked.

Dg273: Black to move Dg273: Start by seeing that the tension in the position is focused on c4: Black has two pieces attacking the bishop there; White has two pieces defending it. This means Black can’t win anything immediately with captures on that square, but if you stop there you're thinking about the position the wrong way. The important question when you have a chance to force a series of exchanges is how the board would look afterwards — what checks you then would have, and whether any of them would be (or could be made into) forks or other tactical devices. Okay, so imagine liquidating the pieces trained on c4. Black plays BxB, and White replies RxB; Black plays RxR, and White replies RxR. The two sides have traded bishops and rooks. More importantly, one of the rooks in White’s battery is off the board and the other ends up on c4, leaving White’s back rank weak (bereft of defenders). The natural thought for Black, then, is to drop one of his own rooks there with check: Rd1+. This forces White’s king to f2—on the same file as

Dg274: Black to move Dg274: You might start here by looking for visual patterns for Black to pursue. The key thing to notice is the spread of pieces on the second rank and especially the White bishops there. Of course there are pieces between them, but if the queens were removed a double attack would be possible; as usual the second rank is a great place for a fork because it can’t be defended by pawns. The bishops there are especially nice targets because unlike the White queen that also is there, they wouldn’t be able to strike back at a rook that jumped between them. So Black goes to work to get rid of the obstructions, starting with the obstructing piece that he can control: his own queen. Experiment with exchanges. If Black plays QxQ,

White plays RxQ. Now only the White rook would prevent a fork of the two bishops. Can it be taken? No. Can something it protects be taken? No. But can the rook be threatened and perhaps driven away? Yes, with Bb4. White moves the rook so as to avoid BxR; and now Black plays Rc2, attacking both of the now-loose bishops and winning one of them.

ten with the rook than with the other pieces we have considered because the rook less often is in position to do both of those things. We consider it here only briefly.

2.4.6. Working with Mate Threats.

Dg276: Black to move

Dg275: Black to move Dg275: What White pieces are loose? The bishop at c3. Black needs a way to attack it and attack something else at the same time— preferably the White king. His queen is off the board, so what might he do with his rook? He can attack the loose bishop with Rd3. That move doesn’t attack the king directly, but the opportunity presented by the loose piece is important, so think harder; examine the White king’s position carefully. The bishop at b6 cuts off the g1 square. The bishop on e4 pins the pawn on g2. So if Black could get a rook onto the h-file, it would be mate. This idea can be put together with the previous one: Rd3 both attacks the bishop and threatens to end the game with Rh3#; after White fends off the mate threat, Black plays RxB. The lesson is to always be aware of the enemy king (not to mention your own) and any of your pieces that constrain it.

Dg276: This time you might begin by inspecting the enemy king (White's) and the constraints on its movement. Black’s bishop attacks h2, and g1 is off limits because White’s own knight is there. So the White king has very limited mobility, and this vulnerability is a tactical opening. If Black could just aim another piece at the king, he might have a mating threat; even if it were easily thwarted, it might enable him to win material by serving as the anchor for a double attack. Best of all would be to land an attacker on h2, since Black already covers that square with his bishop. His rook can prepare to do this with 1. …Rf2. This creates multiple threats at once, which is your general goal as a tactician. The first threat is that White’s queen is now attacked twice and guarded just once (by the knight on g1). If White’s queen moves, either to play QxQ or just to get someplace safer, Black also threatens to mate with Rh2. If White replies to Rf2 with QxR, then of course Black plays QxQ. White’s best reply probably is to play his own rook from d7 to d2, thus preparing to recapture, with a loss, after Black plays RxQ.

2.4.7 Strategic Implications. The motif illustrated by this position—the fork that targets an enemy piece at one end and threatens mate at the other—is familiar from the previous chapters. It occurs less of-

Rooks do not need to be in the center of the board to be effective. In principle, at least, they have the potential to attack the same

number of squares—a full rank, and a full file—no matter where they sit on the board. They generally do need to be moved out of the corners to gain power, however, and moving a rook toward the middle of the board has the particular advantage of making it easier to launch double attacks with the rook against pieces on the same file (i.e., pieces aligned vertically). It stands to reason: double attacks require rooks to get between two enemy pieces; the farther the rook is advanced into the center, the greater the opportunities for enemy pieces to end up on both sides of it. Likewise, rooks on the four middle files are more likely to be able to get between enemy pieces lying on the same rank (i.e., aligned horizontally). Glance at where the rooks that inflicted the double attacks in this chapter generally were positioned at the start of the sequence; ideally, that is where you want your rooks to be: centralized. Whether they do their work out on the board or from posts on the back rank, what rooks most generally require are open files ahead of them. They don’t do much good sitting behind their own pawns unless the pawn is on its way to promotion on the opponent’s back rank. Make it a priority to get your rooks onto open files (or half-open files—files where none of your own pawns sit, even if your opponent still has a pawn in place.) Move your rooks there or move pawns out of their way by making captures with them.

Dg277: Black to move Dg277: Indeed, there is a whole opening—the King's Gambit—premised partly on this idea. White offers to sacrifice his f-pawn on the second move, as shown to the left. What does

this pawn push on the second move have to do with rooks? Everything: once his f-pawn is gone, White will have a half-open file onto which he can bring his rook just by castling on the kingside a few moves later. That rook suddenly can easily become a terror, bearing down on f7— typically a weak point in Black's position. Of course there are many other consequences of the King's Gambit; it's a complicated opening. The point for now is just to see how gaining an open avenue for a rook can be a part of the planning from the first steps of the game. In a sense all this is just another application of some principles given at the end of the chapter on the bishop fork. Here, as there, pawn moves are significant in part because of the lines they open and close. From an offensive standpoint, a pawn capture that creates an open line for a rook may be very valuable for just that reason; from a defensive standpoint, think carefully about any capturing sequences that will have the effect of opening files for your opponent’s rooks. And once a file does open, try to claim it by planting a rook at its base. The positions in this chapter also underscore another point we have seen elsewhere: the importance of creating open lines to the enemy king and of avoiding open lines to your own king. In the rook’s case an “open line” includes the back rank if it can get that far and no defenders are there. Anytime an enemy rook has an open path to your back rank, or a path obstructed only by its own pieces, start worrying. Anytime your own rook is in that position, start experimenting.

2.5. The Pawn Fork.

2.5.2. Exchanges to Create Working Pawn Forks.

2.5.1. Introduction. We now consider double attacks by the pawn. This chapter, too, is shorter than the earlier ones on forks because attacking patterns involving the pawn tend to be simple. A pawn can fork two enemy pieces that are on the same rank and separated by one square. (E.g., the Black rook and knight in the diagram, which can be forked with f2-f4.) Any two enemy pieces are fine, at least if the pawn has protection; the joy of attacking with pawns is that they are worth so little. A pawn for a piece—any piece—almost always is a good deal, so every piece must fear them. And of course you start with eight pawns, and they often are near the combat zones of the board. They can jump from their starting position into the center in one move, and can move diagonally when they capture. We will see pawns taking advantage of all these capabilities in the examples that follow.

Dg279: White to move White looks for a promising geometric pattern and sees that Black has two pieces—the bishop and knight—on the same rank and separated by one square: the classic setup for a pawn fork. The only hitch is that the bishop is an unsuitable target because it can capture the pawn. White asks whether he can take the bishop with another piece, causing it to be replaced by a better target; he can, with NxB. Black recaptures with RxN, and now White plays the fork f2-f4, winning the knight after the rook moves.

Dg278: White to move Dg278: By the way, what will happen in the diagram after White starts with f2-f4? Black might try a classic line of reply to a fork: he can move one of his pieces out of it with check by playing Re1. Now White can't play f4xN; he has to move his king to f2. But White still will make his gains, because now he threatens KxR and (still) f4xN. Black can't escape both threats.

Dg280: White to move Dg280: Here the concept is similar but harder to see. White almost has a pawn fork with d5d6, but the move attacks a queen and a pawn, an unsuitable target. If only the Black king were on e7 rather than d7; and in that fantasy lies the solution: draw the king onto e7 by attacking the pawn there that only the king protects. White plays Rxe7, Black replies KxR (if Black moves the king, White skewers the queen with RxQ), and now the pawn push

d5-d6 wins the queen (the knight on c4 provides the protection the pawn needs to attack it). Notice, by the way, that White does all this while threatened with b5xN. The usual lesson repeats: when under even an obvious threat, consider whether you can effectively go on the offensive with a check of your own. Dg282: Black to move

Dg281: White to move Dg281: The same idea in different form. White sees that his pawn on g3 is one move from attacking the enemy queen on h5. The move would be a lot more interesting if it also attacked something else. There is not yet a working fork because on f5 Black has a pawn—an unsuitable target. So again White asks whether he has anything he can use to capture the pawn and cause it to be upgraded to a target that will work. He finds one option for the purpose: Bxf5+. Black’s only legal reply is KxB, leaving his king and queen in position to be forked with g3-g4. Of course a pawn fork of the queen only works if the pawn has protection, and it does—from the pawn on h3. Again, another way to have seen this would have been to examine every check. White has two: Rb6, which Black escapes easily, and Bxf5, which looks improbable but requires Black to move his king to recapture. You imagine this response, see the telltale resulting position of Black’s king and queen, and take it from there. Dg282: Where does White have pieces vulnerable to a pawn fork?

The knights on e4 and g4 are perfectly positioned. The only obstacle is Black’s own queen at f5. When our own pieces obstruct our plans, our first recourse is clear: try to move them out of the way in a violent fashion that requires a time - consuming response from the enemy. What can Black attack with his queen? White’s queen: 1. …QxQ, 2. e2xQ, and now f7-f5 wins a knight.

Dg283: Black to move Dg283: Where does White have pieces vulnerable to a pawn fork? He has pieces on c3 and e3, and Black has a pawn at d5, so the makings of a fork are in view. There are two obstacles to its success: the White knight on d4 is in the pawn’s way and will need to be cleared somehow; and if a bishop is going to be one of the targets of the fork, the pawn will need protection so it doesn’t get captured. Once you understand that those are the problems you need to worry about, the solution is clear enough: play c7-c5. The threat drives the knight away (every piece flees a pawn), and also creates protection for the d5 pawn when it then moves to d4, forking knight and bishop.

It's worth having a good look at the starting position here. It's important to see the potential for a pawn fork in a situation like this despite all the other distracting pieces in the vicinity—particularly the knight on d4.

pawn on d5 is a square away from being able to fork them. The problem is that d6 is occupied by an enemy pawn. How do we get rid of it? In familiar fashion: take something it protects, forcing it to move to recapture. So White plays NxN; Black recaptures d6xN; and now the fork d5-d6 wins Black’s other knight.

Dg284: White to move Dg284: What Black pieces are vulnerable to a pawn fork? His knight and bishop, of course. What are the obstacles? The Black queen, which blocks the pawn’s path; and again the pawn will need protection if it is going to attack a bishop. The problems here are the same as in the previous problem, and so is the solution: f2-f3 drives away the queen and also provides protection to support the fork e3-e4 that follows. (Note that after 1. f2-f3, Black has to move his queen somewhere; pay attention to where it will go, as its options are very limited. Black likely will play it to h4. Now White pauses to play the exchange 2. QxQ, g5xQ; he plays this first because his own queen is unprotected. Then he plays the fork in the middle of the board.)

Dg286: White to move Dg286: It is White’s turn four moves into the Four Knights opening. He is considering Bc4 to develop his pieces further. What happens if he plays that move? Picture it: his bishop and e4 pawn will be in the classic position to be forked by Black’s d-pawn, and Black would be able to replace the pawn on e4 with a suitable target by playing Nxe4, inviting the reply NxN. Now White’s knight and bishop would be forkable with d7-d5. True, White could then take Black’s pawn with his bishop (Bxd5), but then Black plays QxB. When the smoke clears, Black will have won no material but will have a better position: a pawn in the center and both bishops ready to move. The point of the position is not the precise outcome, though; it is the importance of hesitating before leaving one of your pieces one square away from any of your own pieces or pawns on the same rank. Consider whether your opponent could start an exchange that would create a working pawn fork at the end. 2.5.3. Forcing Pieces into Place with Threats and Checks.

Dg285: White to move Dg285: By now the idea here should be easy to spot: Black’s rook and c7 knight are a square apart on the same rank, and White’s

So far we've dealt with cases where your opponent began with two men ready to be forked by a pawn. One of them may have been an unsuitable target—e.g.,an enemy pawn that

needed to be upgraded with an exchange — but the basic geometric motif already was present. These next positions differ because the geometry for a pawn fork needs to be created; enemy pieces have to be forced onto squares where they can then be forked. How do you force a piece onto the empty square where you want it to go? Sometimes a threat will do the trick. Normally your opponent will move a threatened piece someplace safe, but if it has a limited range of motion because some of its escape squares are blocked or attacked, a threat may force it where you want it to go. Consider this section a general set of lessons in paying careful attention to where threatened pieces will move.

Dg287: White to move Dg287: In this first example White has a pawn that can jump into position to attack the Black queen with g2-g4. The threat is of limited interest by itself, but it would make a terrific first half of a double attack: if Black’s king could be goaded onto f5, White would have a pawn fork. Of course White's knight is there now, and Black's king will want to avoid capturing it precisely because of the fork that then results. But whether these thoughts occur to you or not, on principle you would want to examine every check White can give and its consequences. White has a check at d4 with his knight that achieves nothing. He has checks with the queen at d7 and f7 that lose the queen right away, but another check at e7 where the queen enjoys protection from the knight. How would Black respond? He would have to move the king with KxN. White imagines the board as it would then look and realizes that Black's king and queen would then be forkable with g2-g4.

A loose end remains. When we went over White's checks, we left one out: Re1. It looks good; indeed, it forces the same initial result as Qe7: Black has to play KxN, and now White has that same pawn fork. But there is a grave difference in what follows from there. After White plays g2-g4, Black naturally moves his king away with Kxf4, and then White has g4xQ (the execution of the fork)— but now notice the state of the g-file. White's pawn no longer is there; the only things left behind are White's king and queen: a perfect chance for a pin by Black, which he exploits with Rg8. White can't move his queen, and will lose it next move. White's better starting move, Qe7, avoids this calamity by getting the queen off the g-file right away. The general lesson of this last variation is to be careful to study all of your checks. Sometimes one looks as good as the next for a purpose on first inspection, but turns out to have quite different side effects. The more specific lesson is to be alert to one particular type of side effect: lines that get opened by a tactical sequence, such as the g-file in this case. This last possibility may seem startling and worrisome if you haven't studied pins; but once you get through that part of this project, you will know that the sight of White's queen and king on the same line is something to notice from the beginning here.

Dg288: Black to move Dg288: Look for patterns in the layout of White’s pieces or for threats you can make; the result either way should be to see Black's potential pawn fork d4-d3. The problem is that once the pawn arrives on the forking square it would be attacked twice — by

White’s queen and rook—and protected only once, by Black’s rook at d8. So the pawn gets taken if it steps forward. Yes, but let that sequence play out in your mind’s eye: 1. …d3; 2. Rxd3, RxR; 3. QxR, and now what would be possible on the resulting board? White’s queen and knight would be arranged for the fork e5-e4, winning the knight at f3. In effect the initial fork was just another threat that drew the White rook, then (after an exchange) the White queen, into position for a different fork. Incidentally, note the importance of Black playing the exchange RxR, QxR before executing the fork at the end. If Black plays the pawn fork against White’s rook and knight after the rook has moved to d3, White breaks out of it with RxR+. Once the rook has been replaced with White’s queen, however, White has no good way to break out of the fork. The general points are (a) to always ask whether you can improve the target of a double attack with another exchange, and (b) to always consider what your opponent’s best reply to the fork would be; he may have a check or threat that would enable him to break it—especially if his king is not one of the parties to the fork.

White gets interested in threats he can make against the bishop and their consequences, and looks at a2-a3. Study the bishop’s flight squares and you see that if it moves any deeper into White’s territory it gets taken, so it has to move instead to a5. Now Black’s bishop and knight would be a square apart on the same rank, so b2-b4 would fork them; the pawn on a3 gives the b4 pawn the protection it needs to be able to attack the bishop. The general lesson: keep an eye out for enemy pieces that are hemmed in by their own pieces or by the edge of the board; often they have few options if they are attacked, making the consequences of the resulting sequence easy to predict and sometimes making a tactic easy to execute.

Dg290: White to move

Dg289: White to move Dg289: Sometimes a threat by one pawn will force an enemy piece into position to be forked by another. The previous position was one example; here is another that works a bit differently. White sees that Black’s bishop has limited opportunities for escape, as the knight on c5 cuts off its main line to the rear. (A bishop with so little room to retreat is a vulnerability you want to spot in your opponent's position and avoid in your own.) So

Dg290: The same idea. Again observe that that Black’s bishop has limited motion (look behind it; it can’t retreat toward a7). So White considers threatening it with b2-b4. Here as before, Black’s bishop gets taken if it tries to escape by moving farther into White’s territory. Instead Black might play Bd6—putting the bishop one square away from the knight on the same rank. Now White forks the two pieces with e4-e5, with cover for the pawn supplied by the bishop at f4. (Or Black replies to b2-b4 with the suicide run Bxf2; after White replies KxB, Black has Nxe4+, and White ends up winning a piece for two pawns.) Dg291: This time White's bishop on b5 is the piece with a limited ability to retreat. When you see a piece trapped in this way, think about threats against it. For Black that means

considering Rd5 here. The bishop then gets taken if it moves to e2, d3, c6, d7, e8, or a6. Its only safe move—and it's only temporarily safe—is Bc4. (If White tries Be8, Black plays Kf8 and now the White bishop is attacked twice and defended once with nowhere good to go. Remember that Black's rook would be on d5....) What then would be possible?

Dg291: Black to move

simply pushed it again.) So d5-d6 then wins a knight, with the bishop on g3 providing necessary protection against Qxd6. That is the idea, anyway. Against an alert player the outcome would be favorable but not quite so simple. As usual you need to consider whether he might seize the offensive. Here Black’s best reply to d4-d5 is not to move his knight to c7; it is to play Ne7xd5. Then when White plays e4xN, Black has the recapture Qxd5. White still gains a piece for two pawns, but Black has reduced his losses nicely. There is a valuable defensive lesson in this for occasions when you find yourself the target of an unavoidable fork. If you are destined to lose a piece, you might as well do whatever damage you can with it (or with another piece you can sacrifice in its place). A doomed piece that has this odd sudden liberty to go on a suicide mission is known not as a kamikaze but as a desperado.

White’s queen and bishop would be set up for the pawn fork b7-b5, with Black’s rook at b2 furnishing the cover.

Dg293: Black to move Dg292: White to move Dg292: No Black pieces are poised to be forked. But again it is good practice to examine the consequences of threats you can make by advancing your pawns. White has just one such threat to consider: d4-d5. The Black knight would flee, but don’t stop with that observation; ask where it would go. It has only one safe square: c7. Re-evaluate the board as it then would look and notice that Black’s knights now would be a square apart on the same rank. (Alternatively, after pushing forward a pawn to threaten something, you can always ask what would happen if you

Dg293: The drill: look at any threats you can make with your pawns and ask what consequences would follow. It is especially important to consider this when the threatened piece has little room for escape. Here Black has the simple g7-g6, putting pressure on the queen. The queen’s freedom of movement is limited; it has to move to h4. Now what? Well, Black can attack it again: g6-g5, and now White is in a jam. To see why, consider his king; for it is affected by these movements of your gpawn, which now seals off f4 and h4, and also protects those squares if you want to occupy them yourself. So look for your next check find Bxf4—mate.

This means that after Black's second push of the g-pawn, White wouldn't want to play Qh5. He would need to try f4xg5. Too bad about that f4 pawn of White's. But put this together with the earlier point about f4—its vulnerability to Black's bishop—and a new idea comes to mind: if the pawn at f4 first could be replaced with the White king, Black could fork White's king and queen by putting his pawn on g5. So Black reconsiders that check we mentioned: Bxf4, which he plays early: before or after White’s queen has retreated (naturally you could have found the whole idea here by starting with the check Bxf4). Whether White plays KxB or moves his king to h4, Black’s marching g-pawn then wins the queen.

In the game this position came from, between Tal and Botvinnik, it was White’s turn to move. Tal played Nc3-d5. Now if Black plays g6-g5, White plays NxNf6+. Since this checks the king, Black can’t play g5xQ; he has to capture White’s knight. After that exchange gets rid of the knight on f6, White’s queen has plenty of flight squares and the fire is out. But of course the first important point in all this is for White to recognize that he is in danger. The tipoff is the immobility of his queen.

2.5.4. Forks By Marching Pawns.

A similar result can be reached by skipping Bxf4+ at the beginning and just playing 1. …g7-g6; 2. Qh4, g6-g5; 3. f4xg5—and now 3. … Bxg5 attacks and wins the queen. The bishop has protection against capture, and if White tries to move the queen to safety on h5, Black has f5-f4. This forces Kh2, which in turn allows Black to play Rh1#.

Dg295: White to move

Dg294: Black to move Dg294: This time White’s queen is the piece that is cramped: it’s up against the side of the board with little room to retreat. Black considers a threat against it with g6-g5. Where will the queen go? It gets captured if it moves to h5 or to anywhere on the fourth rank (look and see). So it has to move to h3. Yet now its relationship with the knight on f3 calls for a pawn fork: g5-g4 wins the knight, with Black’s own knight at f6 supplying the needed protection for the pawn.

Dg295: White looks for promising patterns and sees Black’s queen and knight in a vulnerable position: a square apart on the same rank. White has no way to get a pawn onto c5 in one move, but perhaps he could march it to c5 by threatening something with it along the way. The small push c3-c4 threatens Black’s knight; after it flees, c4-c5 then forks queen and knight—with the necessary cover supplied by White’s own knight on b3. When you find a sequence like this, of course, you understand that it is the ideal sequence. Your opponent may make sacrifices to prevent it from playing out quite as you imagined. Thus after White plays 1. c3-c4, Black’s best option is not to move his knight and allow the coming knight fork. It is to launch a counterattack with 1. …Bf5, attacking White’s rook. It's a nice attack; for if White moves his rook to a1 or c1, Black then plays Bxb2 with his dark-squared bishop and now

the rook has no escape. So White's best reply to Black's Bf5 is to forget the rook and play 2. c4xN, BxR; 3. QxB, Nxd5. White has won a knight and a bishop for a rook and a pawn.

no checks in the picture), because he may then be able to buy time by making similar or worse threats of his own elsewhere. In this case it's not an issue, however, White has no effective way to derail the fork.

Notice that in this sequence the pawn fork never actually gets played. It has to be seen, though, because the threat of it causes everything else that happens instead. In good play, forks and similar tactical devices frequently do their most important work in this indirect way: they are seen and avoided, but the effort to avoid them forces material or positional sacrifices that end up being decisive.

Dg297: White to move

Dg296: Black to move Dg296: Here is a similar position. What White pieces are poised to be forked by a pawn? The bishop and knight on f3 and h3 are in the classic position. Black can’t get a pawn onto g4 in one move, but he can march it there, and leave White no time to defend itself, by playing g6-g5, threatening White’s f4 bishop. The bishop runs away, and now g5-g4 wins a piece. (The Black pawn on f5 provides the necessary cover, of course.) Here as in the previous position your opponent can thrash around a bit; after the initial pawn push, White can throw in a capture elsewhere like c4xd5. In this case Black just recaptures with his e-pawn and the forking threat is both renewed and unavoidable for White, but the point is that you always want to make sure you have considered what counterplay your opponent might be able to offer elsewhere on the board. This is especially important when the sequence you contemplate doesn’t threaten the enemy with anything more than the loss of a piece (i.e., you have

Dg297: The same idea once more. The first thing is to train your eye to see two pieces lined up with a single square between them, as Black's queen and knight are arranged in this case. White can’t get a pawn to e5 in one move, but he can do it with a two-step push: e3-e4 forces the bishop to move because the pawn is protected three times (count 'em). Now e4-e5 wins the knight after the queen moves; this time the rook on e1 provides the needed cover. Black has no effective counterplay here, but as an exercise imagine the position with White’s pawn on h3 moved back to h2. Can something so subtle make a difference? It does: for then after 1. e3-e4, Black has 1. …Ng4—threatening mate with Qxh2. The mate threat can be evaded in various ways (e.g., with 2. BxN, BxB; or with the simple 2. e4-e5, forcing Black’s queen to retreat), but now the forking threat is over because Black's knight has left f6. There are a few lessons to take away from the variation just discussed. Again, especially when you are not operating with checks you have to ask what threats (particularly what checks and mate threats) your opponent might be able to make as an alternative to playing into your hands. In this case you would want to be especially wary of moves he can make by either of the pieces being threatened, and

wary as well of threats against your king's position. If an enemy queen already is aimed at a square next to your king, as Black's is here, remember that your opponent may be able to create a mate threat by simply adding another attack against that square. Maybe the mate threat can be defused easily, but it will cost you time. Finally, you can treat this as a little study in the value of a well-placed pawn. In the position as actually diagrammed, the pawn on h3 is doing quite helpful work by keeping Black's f6 knight from jumping to g4. This is an important office of pawns: guarding squares where you don't want enemy knights planted.

moving is what it used to protect that may now be loose.) Now let’s think about counterplay for a moment. After c2-c4, is it clear that Black has nothing better to do than move his knight out of the way and allow the fork on c5? What attacks of his own does Black have as options? He can play BxB, freeing one of the pieces to the potential fork with a capture; the question is whether, after White recaptures h2xB, Black has bought time to rush his knights to safety. Almost, but not quite. For when Black played BxB, the knight on d5 became pinned to its king and thus cannot now be moved. So after White recaptures on g3, the best Black can do is take the c4 pawn with his other knight (Nb6xc4), thus allowing White to play RxNd5 next move. White wins a piece for a pawn, but again the sequence is not quite as simple as it might look at first.

Dg298: White to move Dg298: White sees that Black has left two pieces—his bishop and his b6 knight — a square apart on the same rank, inviting a pawn fork. White’s c-pawn needs two moves to get there, which is fine so long as the first move is a threat that requires a timeconsuming reply: after c2-c4, the knight moves, and then c4-c5 wins a piece by forking the knight and bishop. But wait; where is the cover the pawn needs before it can attack a bishop that has the power to capture it back? There is none, but none is needed because after the knight on d5 moves the bishop is pinned to its king by White’s rook on d1. Recall that even if a target looks unsuitable because it can defend itself, it is powerless to do so if it is pinned; thus whenever a piece moves, as the d5 knight does here, consider whether the move creates any open lines, any pins, etc. (If Black were to reply to the initial pawn push with Nb6xc4, he would be leaving his other knight exposed to RxN; another question to ask when you imagine a piece

Dg299: Black to move Dg299: Black experiments with the effects of advancing a pawn and finds that e4-e3 moves near to forking White’s queen and rook. Of course White wouldn't allow that; but go farther and ask precisely what he could do to prevent it. (a) White won't be playing d2xe3 because the d2 pawn is pinned to his queen. (In other words, Black would have QxQ; if White then replies RxQ, Black plays RxR#.) (b) If White responds to e4-e3 by moving his queen out of the way (say, to c2), Black plays QxR#.

(c) If White moves his rook to g1, Black can't quite play BxR, because his own pawn would be blocking the way on e3. But he can use that pawn to take White's pawn on d2, and thus threaten to take the c1 bishop next move; once White avoids that threat (with Bb2), then Black has BxR after all, winning the exchange and a pawn after White recaptures. (d) So suppose White instead plays Re1. This, too, fails—to e3xd2, forking rook and bishop. White plays Bxd2, and then Black has QxB, winning a piece. The important thing to notice is how a pawn can march not only forward but also diagonally by making a capture, expanding its potential to inflict forks. And then there is a larger point to observe: the pressure on White’s king that indirectly drives the tactical sequence here. The king is stuck in the corner; the Black queen’s threat to mate on White’s back rank (QxR) effectively freezes White’s queen in place, as it must defend against this possibility. These pressures on White’s king do not enable Black to mate, but they do constrain his other pieces severely enough to make a capture of material possible. It is important to appreciate how such accumulations of pressure against one point—especially though not only against the king—can end up paying off with gains elsewhere as your opponent has to make sacrifices for safety’s sake.

compensation. But Qd3+ forces White to play QxQ, to which Black replies e4xQ. Now reexamine how the board would look: the pawn on d3 would be attacking the White knight on c2; and if the knight moves, the pawn advances to d2, forking both rooks. Could it then be taken by the king? No, because the knight formerly on c2 will have moved, creating an open line for the Black rook on b2 to provide cover for the pawn. So White is better off letting his knight on c2 get taken by Black’s pawn rather than letting the pawn march farther and take a rook. Think of this as a case where a pawn again marched diagonally with a capture, enabling it to deliver (or threaten) a fork that would not have been possible on its original file. But in order to move over a file, the e4 pawn needed White to put something on d3 that it could take; the something—White’s queen—was drawn into place with a check (Qd3+).

Dg301: Black to move

Dg300: Black to move Dg300: Here is a nice extension of the principle we are studying. Black examines every check as a matter of course, and finds two: Qe2 and Qd3. Qe2 loses the queen without

Dg301: Another extension of the principles in this chapter. Black’s possible checks (Nc3, Qf1, Qxc2) don’t seem to go anywhere, so he experiments with captures and their consequences. Nxb2 is interesting because White’s only way to recapture would be with his king; any exchange that causes the king to move is interesting. Now what do you see in the resulting position? The king and d2 rook are left a square apart on the same rank, in position to be forked by a pawn on c3. Black has no pawn on the c-file. He does, however, have a pawn on the b-file that is close by; if that pawn could capture something drawn onto c3, it could execute the fork. One way to get an enemy piece onto a square, as we have seen,

is to put one of your pieces on the square in a threatening way that requires the enemy to recapture there. Best of all is a check. So Black plays Qc3+, a move that attacks both White’s king and queen; White has to play QxQ (White’s king can’t capture the Black queen because the queen’s square is guarded by a pawn; and if White moves his king, his queen gets taken with QxQ). After White’s QxQ, Black plays b4xQ+—forking king and rook with cover from Black’s own rook on c8. Black in effect has traded a knight for a rook. Again, see how the pawn was able to move over to deliver a fork on a different file after Black drew a White piece onto that file that the pawn could capture. Now remember that all this assumes White replies to Black’s initial Nxb2 with KxN. White doesn’t have to do that; he can skip the recapture, and indeed is better off doing so— in which case Black wins a pawn rather than the exchange. It is another case where the threat of an eventual fork, if appreciated by both sides, leads to indirect gains.

2.5.5. Strategic Implications. Now a few thoughts on the strategic implications of our work on pawn forks. An easy way to get nailed by a pawn fork is to allow one of your pieces to get trapped on a square where it has limited motion. Bishops and knights near the side of the board are especially vulnerable to this type of trouble; a knight has a maximum of eight flight squares when it is well-placed, but when it’s on the side of the board it may have only four or even fewer, and then it is easy for some of those squares to be occupied by its fellow pieces or to be under attack by the enemy. Likewise, a bishop in the middle of the board may be able to move in four different directions; but a bishop on, say, a5 with one of its own pawns behind it on b6 can only go one way, and has a maximum of four escape squares. There are lots of ways for pieces stuck in this way to be taken by pawns, either directly (they simply get trapped) or by being

threatened in ways that force them to move onto squares where they get forked. There is additional reason to worry whenever you see pieces being used as defenders of other pieces—or of pawns. For then if the man under attack gets taken, it is replaced by a new valuable target that may be loose or underdefended. When you do protect your men with other pieces, remember that as soon as the protectorate gets taken,you will be forced to move the guarding piece onto a square of your opponent’s choosing. There it may become a target. It may be loose; it may lack the defensive powers of the piece it replaced; it may have greater value than the piece it replaced. Thus we saw a number of examples in this chapter of exchanges where pawns were taken and pieces performed recaptures—and then the pieces got forked. Lesson: when you press a piece into service protecting a pawn, give thought to the danger that it can be drawn onto the pawn’s square with a capture. Since pawn forks often are the residue of exchanges initiated by pieces (a bishop takes a piece and gets recaptured; then comes the pawn fork), it follows that you can expect better success with pawn forks when you have a well-mobilized army—pieces on open lines attacking lots of enemy squares and putting pressure on enemy pieces. Those are the positions that give rise to exchanges that make pawn forks and other double attacks possible. Notice generally, too, that victims of pawn forks often do not have good control of the center of the board. For a pawn to fork two pieces it often has to pass through the center or be operating in a sector where it is more advanced than the pawns on the other side (otherwise the enemy pawns interfere with its attacking movements). Pawns established in the center are most likely to be in a strong position to make or threaten forks because it is easy for enemy pieces to gather on the same rank in their own territory where enemy pawns in the center can reach them.

Chapter 3: The Discovered Attack.

3.1. Bishop Discoveries. 3.1.1. Introduction to Discovered Attacks Generally. In a discovered attack, or “discovery,” one of your pieces moves out of the way of another, unleashing attacks on two enemy pieces at the same time—one by the unmasking piece and one by the piece unmasked. The enemy only has time to protect one of the threatened pieces. You take the other one. The diagram on the left shows the idea in skeletal form. If White plays his knight to f6, it gives check while unmasking an attack by his queen against Black's queen. Black only has one move to respond to these two threats, and he has to spend it moving his king to safety. Then White plays QxQ. This at least is one of the patterns (a knight discovery) in its classic form; there are many variations on the theme that we will consider in due course. Discovered attacks always involve two offensive pieces: an unmasked piece and an unmasking piece. Every piece has the power to unmask attacks by others by moving off of lines that it occupies. Not every piece has the power to be unmasked, though; a knight, for example, can't be unmasked because it can't be masked in the first place: it jumps rather than slides, so it doesn’t move along a line that can be temporarily blocked by a fellow piece. But the knight is a magnificent masker and unmasker of attacks by other pieces. Conversely, the queen is a great piece to unmask, but not a good masker of other pieces. It can’t hide an attack by a rook or bishop because a queen can make all the same moves that either of those other pieces can; if a queen masks a threat by a rook, it already makes the same threat the rook would. The essence of a classic discovered attack is that before it is executed, neither piece directly threatens anything. After it is executed, both of them do. The plan of this section will be to take each of the major unmasking pieces—the bishop, the rook, the knight, and the pawn—and study one by one how they can unveil attacks by other pieces: what the unmasking piece looks

like when it is poised to do this, how the germ of such an opportunity can be created, and how such ideas can be perfected and executed once they come into view. We will identify the visual patterns that signify the possibility of a discovered attack and practice identifying them until it becomes habitual. Mastering discoveries means learning new ways to think about the pieces and the relationships between them. You may be accustomed to thinking of bishops as pieces that attack diagonally and to regarding rooks as pieces that attack back and forth and from side to side. That’s not wrong, but it’s incomplete. Bishops attack diagonally and unmask vertical and horizontal attacks by rooks and queens. Rooks attack vertically and horizontally and unmask diagonal attacks by bishops and queens. Make it one of your goals to think of your pieces not just as individuals but as partners—as parts of a team whose efforts need to be coordinated. Discovered attacks are an example of coordination, as each partner makes the other more powerful; a bishop and rook on the same file, with the former masking the latter, often has far more destructive power than either piece by itself. Every discovered attack starts with a kernel consisting of two pieces: the piece to be unmasked and the piece that will unmask it. Once found, a kernel can serve to organize the rest of your thinking about what to do: you start looking for targets for each piece or ways to clear the lines between the pieces and their targets. We will be studying discovered attacks one kernel at a time: first the one where the bishop masks a rook or queen on the same file or rank; then the kernel where the rook masks a bishop or queen on the same diagonal; and so forth. We will emphasize spotting the kernel of a discovery because the practical importance of training your eyes in this way is so great. If you don’t see the basic pattern when it's there, all the skill in the world at perfecting it won't be of much use.

3.1.2. Introduction to Bishop Discoveries

target needs to be an unguarded bishop or else a protected piece that is more valuable, such as the enemy queen (whether it's guarded or not). But now we're getting a little ahead of our story. Let’s start by studying some positions involving discoveries by the bishop in simplest form. 3.1.3. The Classic Pattern.

Dg302 We begin with discoveries where the bishop unmasks an attack by a queen or rook running up the board or from side to side. The position on the left is a skeletal illustration. If White moves his bishop to c4, it checks Black’s king; the bishop’s move also unmasks, or “discovers,” an attack by the White rook on Black’s queen, which White will win next move. The job of the piece in front is to give check and thus keep your opponent busy; the piece in the rear then has its chance to carry out a capture. This is the typical pattern, though there are others we will study later. Before a discovered attack is unleashed there always are three pieces in a line on a rank, file, or diagonal: the masked piece, the piece about to unmask it, and the target. When the bishop is doing the unmasking, the three pieces always are on a file or a rank. That is the kernel to look for in the positions that follow: a bishop blocking the path of a rook or queen. Then we'll follow up with standard questions: whether the two pieces in the kernel both have good targets, or whether targets might be created for them; whether the needed lines are clear or can be cleared; etc. We also can work toward discovered attacks by thinking about the suitable targets for them. Bishop discoveries always unmask attacks by queens and rooks. It follows that the target of the unmasked piece usually needs to be a queen or a loose piece for the attack to turn a profit. Unmasking an attack by your rook against a protected bishop, for example, isn't going to scare your opponent; the rook's

Dg303: White to move Dg303: We start with simple positions where a discovered attack is ready to be executed: one piece masks another, and both have good targets. Visually most of these positions will take a common form: a bishop moves from the middle of the board to the edge near the enemy king, where it gives check or makes a capture; in the process it unmasks an attack up the board by a rook or queen, usually made from the back rank. In the diagram to the left, notice the position of White’s rook and bishop on the d-file—a classic kernel of a discovered attack. The bishop masks the rook; if it can vacate the file in a forceful enough manner—e.g., with a check—White will have the capture RxQ a move later. So White plays Bxh7+; Black is forced to spend a move protecting his king with KxB; and now White takes Black's queen with his rook. After Black recaptures with RxR, White has traded a bishop and rook for a queen and a pawn. Dg304: Find the kernel of a discovery for Black. His bishop on d6 masks the Black queen’s path up the d-file.

pawn on h2 or h7 and thus giving check to the castled king as we saw in the previous cases; but as this position shows, you want to look for every possible check you may be able to give with the unmasking piece.

Dg304: Black to move Meanwhile White’s queen is loose on d3. If Black can use the bishop to give check, he will be able to play QxQ afterwards. Black thus finds and plays Bxh2+. White is forced to play KxB (or NxB), and now Black takes White’s queen. There were lots of ways to see this move: the three pieces aligned on the dfile were a tipoff; or you might have set out to examine every check, found only Bxh2, and noticed that as a consequence of that move the d-file would be opened—and also seen that White’s queen is loose. Above all, however, study the relationship of the Black bishop and queen here. The most important thing about the bishop in this position is what it masks.

Dg306: White to move Dg306: The relationship between White’s bishop and rook on the b-file should jump out at you: never fail to notice when pieces are paired like this, as it signals a possible discovery. Here White has a good target in Black’s loose queen, so he looks for a check he can give with his bishop and finds Bxf7+. Of course the move is useless as a serious threat to Black’s king, but its purpose is just to create a distraction. Black has to capture the bishop or move his king, and now White plays RxQ.

Dg305: White to move Dg305: An almost identical pattern seen from White’s side. You notice that the bishop masks the queen on d1; the queen otherwise would be able to take Black’s queen, which is loose. So White clears the bishop from the dfile and creates a distraction at the same time with Bg6+. Black has to address the check; after he takes White’s bishop, Black’s queen is lost. The more common checking move in this sort of position has the bishop taking the

Dg307: White to move Dg307: The most important purpose of these first positions is just to train your eyes to see a single pattern: a bishop masking an attack by a rook or queen on the same file. Here the pieces are farther apart than before, but the pattern is structurally the same. White’s job is to move the bishop out of his rook's way violently—preferably with a check. Bg8+ does

the job: another example of a less usual check, as the bishop attacks the king from the rear. White will play RxR next move, winning the exchange.

for a check or other violent move to give with the bishop, and plays Bxf7+. However Black responds to this check, White next plays RxR and wins the exchange.

3.1.4. The Unmasking Piece Makes a Capture or Threat.

Dg308: White to move

It isn't always possible for the unmasking piece to deliver a check, nor is it always necessary; any move that creates two threats at once has winning potential. Here are some positions where the unmasking piece makes a capture or threat that serves the same distracting purpose as a check.

Dg308: Where does White have a possible discovered attack? On the side of the board, where we find the familiar kernel of bishop masking rook on the same file. There is an easy target: again Black has a loose rook, this time on a7—a valuable enough piece to justify sacrificing the bishop if necessary. White looks for a check the bishop can give as it moves out of the way. He finds Bc4+, a nice backward move that wins the loose rook without need of a sacrifice. Dg310: White to move

Dg309: White to move Dg309: White has a bishop with a rook— indeed, two rooks—behind it on the same file. The arrangement signals the possibility of a discovered attack. White has a fine target for the rooks on c8. True, the rook there is protected by Black’s other rook at f8; but since White has two rooks trained on the square, the target is attacked twice and protected only once and so is as good as loose. White looks

Dg310: In this first position, White's bishop and rook on the c-file are in the characteristic formation for a discovery, with Black’s loose knight providing a suitable target. White just needs to vacate the bishop from the file forcefully. The types of moves considered in the previous section won’t work here because White has no checks. But he has another violent move at his disposal: BxN, taking a knight and threatening the rook on f8. Black’s king isn't threatened, but he nevertheless must redress his loss and protect his rook with KxB—after which White can play RxN, winning a piece. Dg311: Black's bishop masks an attack by his queen against White’s loose knight on the efile. Black looks for things he can do with his bishop that will keep White busy and allow QxN a move later. The bishop has no checks and no good captures; so Black considers eve-

rywhere the bishop can go, searching for a threat.

Dg311: Black to move He finds Bh3: not a check, but a threat against White’s rook. White either loses the knight or trades a rook for a bishop, forfeiting the exchange. When you launch a double threat without a check at either end of it, as Black does here, you have to be especially careful to think about your opponent’s options in reply. Since you haven’t given check he will have a freer hand than he otherwise would; maybe he can give check, wrest away the initiative, and escape your attack. In this case Black needs to notice that White has a check available in Qa4. Is this trouble? No, because Black can meet it with b7-b5. But the point still holds: don’t go forward with a tactical sequence — especially one that doesn’t give check — without considering checks your opponent can throw at you in the middle of it.

Dg312: White to move Dg312: The same idea in slightly different visual form. White's bishop and rook on the dfile, of course, create a possible discovery

against Black’s loose bishop. To unleash it White needs a violent and distracting move for his own bishop to make. As the piece can't give check or make a good capture, White looks for threats the bishop can make and sees that it can attack the rook on b6. There are two ways to do it: Bc5 or Bc7. Which is better? Answer: Bc7 is better. In reply to Bc5 Black could play Rb7, both moving the rook to safety and using it to protect the bishop on d7. Bc7 not only threatens Black’s rook and bishop at the same time, but also makes Rb7 an ineffective reply. White wins the bishop. Notice the general point, though: you always want to be mindful of any way the enemy might be able to move the target and address your other threat in one stroke.

Dg313: White to move Dg313: You see White’s bishop masking his rook; you see that the rook would attack Black’s queen if unmasked; you look for a move by the bishop that would take advantage of the situation. The bishop's only capture, Bxh6, would be of no great concern to Black. But look as well for threats White can make that would have to be taken seriously. Again White can use the bishop to threaten Black’s rook, this time with Bf4. After Black moves his queen to avoid RxQ, White takes the rook and wins the exchange. Most often the point of a discovered attack is that the unmasking piece—the bishop in these examples—is sacrificed or creates a timeconsuming threat so that the unmasked piece can capture an enemy target. But here the unmasked piece (the rook) creates the time-

consuming threat, effectively allowing the unmasking bishop two moves: one to line up against Black’s rook, and the other to take it. Whichever piece plays the primary attacking role, the logic of the tactic is the same: you launch two attacks at the same time, leaving your opponent time to deal only with the more pressing of them. Soon we will give more detailed consideration to the most important positions where the stationary piece does the distracting and the unmasking piece does the attacking: the discovered check.

Note that you want to consider all the ways White could reply to the mate threat—and especially any replies that also take the White queen out of harm’s way and thus blunt both ends of the fork. Here White could respond to Bg1 with Qh3; suddenly neither part of the fork works. But Black still wins because now the d-file is clear for him to play RxR. This position involves an important type of threat to remember: a threat not against a piece, but against a vulnerable square next to the king. When you have a piece aimed at a square adjacent to the enemy king, aiming another piece there may create a threat of mate; and if it does, that square can become a target just as sensitive as the king itself.

3.1.5. Drawing the Enemy King into Place.

Dg314: Black to move Dg314: Black’s bishop masks his rook on d7, and the rook is aimed at White’s queen. What can he do with the bishop that will require a time-consuming reply from White? He has no checks or captures, so he looks for threats (and of course you would want to look for threats even if there were a capture to make; the threat might be the better move). With no White pieces on dark-colored squares, the bishop’s prospects for threatening anything may seem dim. But your assessment of a position always should include an inspection of the enemy king and the pressures bearing on it—the constraints on its movement, and its exposure to checks. Black has a single check: Qxh2. By itself that move wouldn't be productive, because the queen would have no protection against KxQ. If the bishop could add pressure to the h2 square, though, the possibility of Qxh2 would become a mate threat. Is there a way for the bishop to attack h2? Yes, with Bg1. Of course White escapes mate with KxB, but mate isn't the goal; the goal is to require Black to address the threat of mate and thus create time for the point: RxQ.

What do discoveries look like when they lie two or three moves away? For openers, consider that a working discovery requires two enemy targets: one for the unmasking piece to threaten to create a distraction (ideally the king), and one for the unmasked piece to capture after the distraction does its work. In the positions to this point both of those targets have been in place from the beginning. Now let's see some cases where one of the targets needs to be drawn onto place. The best target for a piece that unmasks a discovered attack is the enemy king because a threat to it must be addressed by your opponent and his options will tend to be limited and safe for you. The king usually can’t escape the check by running off to protect the other piece you are threatening or by inflicting a threat of its own. It moves too slowly. So when you have some of the ingredients of a discovery in place, it’s worth some trouble to try to get the king into position to be checked by the unmasking piece. The most common ways of moving an enemy king are by checking it with another piece or by capturing a piece that the king protects. Dg315: In the example, White has the queenbehind-bishop kernel of a discovery in place,

with Black’s queen ready to be taken on d5 if White can find a big enough threat to make with the unmasking piece. Since White is going for Black’s queen (and since moving the bishop exposes White to the risk of QxQ), the threat the bishop makes needs to be against Black’s king to be effective. Can the bishop give check?

els on the light squares and the king is on a dark one. Again, try handling this by checking the king with another piece, thus forcing it onto a light square where it can be checked by the bishop. Black can give check with his rook in two ways: Rd2 and RxB. After Rd2+ White can move his king to, say, g1 with nothing accomplished for Black. But in reply to RxB+ Black has to recapture KxR — moving his king onto a light square. (If White instead moves his king, Black plays RxQ — a skewer.) Now Black checks with Bd3+, unveiling a threat against White’s queen that White has no time to fend off.

Dg315: White to move No, not yet; White’s bishop travels on the dark squares, and the king is on a light one. So the first thing to consider is giving check with another piece in hopes of forcing the king onto a square where it can be checked by the bishop. White has one check he can give without ruining the discovery he is planning: Rh8+. Black would be required to play KxR—moving his king onto a dark square. Now White can check with BxR+; and after Black plays KxB, White has QxQ.

Dg316: Black to move Dg316: Black has the makings of a discovered attack on the f-file, where his bishop masks the capture QxQ. If only the bishop could vacate f5 and attack White’s king. At the moment it can’t be done; the bishop trav-

Dg317: Black to move Dg317: Black has the kernel of a discovery on the d-file: his bishop masks his queen, which otherwise could take White’s queen. White’s queen is defended by its king, however, so QxQ would not yet be profitable. And there is another problem: What unmasking move could Black play? We look first for a check the bishop can inflict and find Bb4, but one always must consider what the reply to such a move would be; sometimes your opponent will have an answer that fends off the check and the unmasked threat. This is such a case: Bd2 would stop both of Black’s threats. (Another possible sequence would be 1. …Bb4+; 2. a3xB, QxQ; 3. KxQ, Nxf2+ (a knight fork); 4. Ke1, Nxh1; 5. Bg2 (where the knight has no escape)—and White is okay, as he has won a queen and two pieces in trade for a queen, and pawn, and a rook.) Still, for Black to have the kernel of a discovery in place like this, with the enemy queen at one end of it, is an opportunity not to be abandoned lightly. Black looks for ways to

move the White king by checking it with his other pieces and finds none. But there is another way to force a king to move: capture something on a square next to it—a square only the king protects, so that it has to move to recapture. Nxf2 comes to mind, as it not only captures a pawn but forks White’s queen and rook. Suppose White then plays KxN. Now how would the board look? The bishop on d6 would have a check with Bxg3+, and this time there would be no way for White to defend against it while also protecting the queen—which would have been left loose when the king moved away. So now the discovery works.

The discovery would work better, and would indeed look like many good discoveries we have seen, if a more valuable piece—i.e., Black’s queen—could be made the target of the unmasked rook. The method for arranging this is simple: when you are confronted with an unsuitable target like the d7 knight here, ask whether you can first take it with another piece and what the consequences would be. Here White can capture with BxN; Black’s only recapture is QxB. If Black goes through with that move, the exchange has caused the bad target to be replaced with a good one. Now Bxg7+ unmasks a classic discovered attack against Black’s queen, which is lost after Black fends off the check.

3.1.6. Drawing the Target into Place. Suppose your unmasking piece is one move away from giving check or inflicting some other terrible threat; the problem is that the masked piece has nothing suitable to attack. Perhaps the target at the other end of the file is protected, or not very valuable. Again, there are some standard ways to try to draw a good target into the path of the discovery. Dg319: Black to move

Dg318: White to move Dg318: In the diagrammed position here, White has the kernel of a discovered attack on the d-file. The bishop has a good threat to make: Bxg7 gives check. But the rook behind it lacks a good target once it is unmasked. It can take the knight on d7 (and avoid being recaptured because it would have cover from the bishop on b5); but meanwhile the White bishop would have been sacrificed, so the net gain for White would only be the pawn on g7.

Dg319: Black has the kernel of a discovery on the d-file: the bishop is poised to give check with Bxh2 and unmask an attack by the rook at the same time. But an attack against what? The only target on the d-file is White’s pawn, which anyway is protected. Again, in this situation consider whether you can take the bad target with one of your other pieces, and so cause it to be replaced by a valuable one. Here Black can take the pawn with his bishop, which after Bxd3 threatens both White’s queen and his rook on f1. White has to play QxB if he wants to avoid losing the exchange to BxR—but after QxB, the board is arranged for the discovered attack Bxh2, sacrificing a second bishop to win the queen. Dg320: Spotting the kernel of the discovery for Black on the d file should be habitual by now. The challenge is to diagnose and cure the impediments to its success. The first is that the bishop on d6 lacks a good threat; it is

aimed at h2, where it could give check, but its path is blocked by its fellow knight. The second problem is that the rook on d8 lacks a good target.

Dg320: Black to move If the bishop were vacated from the d-file, the rook would be directed at White’s bishop, which is guarded. Once you clearly understand these obstacles, ideas for getting rid of them at the same time suggest themselves: move the Black knight out of the bishop’s way, and in the process use it to capture the unsuitable target on d3 and cause it to be replaced by something better. Thus NxB, and now if White wants to avoid the loss of the piece he has to recapture QxN. Now both problems have been solved. The Black bishop’s path to h2 is open, and Black’s rook has a good target in the queen on d3.

think about what it would take to make the tactic work. (a) First, the pawn on c7 would need to be replaced by a better target. So consider taking the bad target with one of your other pieces (like the White knight on b5), and ask whether your opponent would have to recapture with a more valuable piece. (b) Second, it would help to have a better target for the unmasking bishop to threaten— preferably Black’s king, which unlike its queen would not be able to move and cause trouble when attacked. Black’s king is behind its queen, but the queen protects the same pawn on c7 that we are trying to trade for a better target. The solution to the problems at both ends becomes obvious: White plays Nxc7; if Black recaptures QxN, White has a check for his bishop with Bxe6 and a target for his queen in the loose Black queen on c7. The lesson repeats: be clear about what obstacles prevent your idea from working; often two problems can be solved with a single stroke.

3.1.7 Clearing Needed Lines. In the last two positions the discovered attack required a preliminary exchange that both improved the target the unmasked piece would attack and opened a line for the unmasking piece to use to make a threat against the enemy king. We now look more closely at this last principle: identifying lines that need to be opened to make a discovery work, and clearing them with exchanges and threats.

Dg321: White to move Dg321: Where does White have the makings of a discovered attack? On the c-file. But once more only the queen-behind-bishop kernel is there; the queen lacks a good target, and the bishop has no checks to give, although it can attack Black’s queen with Bxe6. So again

Dg322: White to move

Dg322: In the diagram position, start the standard identification of the kernel discovery. Here it's on the d-file, where White's rook is aimed at Black’s queen at the other end of the board. The difficulty—both in seeing the kernel and in perfecting it—is that White has two bishops in the way. If one of the bishops could be cleared from the file in a manner that is time-consuming for Black, the board might be set up for an effective discovery by the bishop that remains. Each bishop has a possible threat (try imagining the board with one of them removed, then the other): the d3 bishop can go to c4 and threaten Black’s rook on a2, and the d4 bishop can capture Black’s knight on f6 and threaten to take another piece from there. So first White plays Bc4, requiring Black to respond by moving the rook to a8 or perhaps a5; and now the way is clear for White's other bishop to play BxN. Black has to spend his reply move saving his queen (this is one of those discoveries where the threat by the unmasked piece is greater than the threat by the unmasking piece). Notice that after White plays BxN, Black could try to take the offensive by playing his e7 bishop to c5—a move that seems to expose his queen to capture, but actually is quite safe because it gives check (when White played BxN, he created an open diagonal to his own king). Now if White moves his king, Black can play QxBf6; in other words, the Black bishop's move to c5 was another discovered attack. But White has an answer: he can block the check and save his piece by simply retreating his bishop to d4, having already won a piece. We see again a recurring point: don’t forget to look for checks you opponent might be able to throw into the middle of the sequence you are planning. They can ruin your plans by buying him time to move his pieces out of harm’s way. It’s not a problem here, however, because White has an excellent answer. Now think about one other way things could go. Black could respond to the initial move 1. Bc4 by moving his queen to a8 to protect his rook; his plan this way would be to lose just the exchange rather than a whole piece. But play it through in your mind’s eye: White

plays 2. BxR; Black replies with QxB; but now the queen ends up in cramped territory, which should worry Black. What happens if White throws an attacker at the queen with Ra1? The queen turns out to have nowhere safe to go. So Qa8 as a first response for Black doesn’t work out. Again, though, the important lesson is general: if you attack an enemy piece as part of a double threat, realize that he might be able to reply by adding to its protection as well as by moving it. If he does add to its protection, imagine going ahead with the capture and permitting him to recapture, and ask how the board would then look. Obviously this practice would be just as important if you were playing the Black pieces here; else you might lose your queen. Finally, let’s return to the initial diagram to emphasize the most basic point of the position: if you see the skeleton of a discovered attack but with extra pieces in the way, think about how you might clear the obstructions in a forcing manner that cuts down your opponent’s choice of replies—i.e., with checks, captures, and threats. Here a simple one-move threat by the d3 bishop forced Black’s reply and made possible a classic discovered attack. More broadly the position shows the importance of seeing the kernel of a discovery even when there are other pieces also cluttering the line.

Dg323: White to move Dg323: White’s bishop masks an attack up the d-file; this time the potential attacking piece is White’s queen. White’s bishop has an obvious place to go that will cost Black some time: Bxh7+. The problems are that Black’s queen—the natural target of the operations—

is guarded by a knight, and that the Black pawn on d4 blocks the d-file. Start with the second problem; examine how the pawn is threatened and defended. It is attacked by White’s c-pawn and two knights, and defended by a knight, a bishop, and a queen. Play through the liquidation of those pieces in your mind’s eye and see what is left at the end: 1. c3xd4, Nxd4; 2. NxN, BxN; 3. NxB, QxN. With the board thus simplified, what would be possible? The c and d pawns would be gone; both of White’s knights would be gone; Black’s knight and bishop would be gone; and Black’s queen would be loose on d4, in front of White’s bishop—a classic setup for a discovered attack via Bxh7. After Black plays KxB, White plays QxQ, winning Black’s newly loosened queen. This position looks a little complicated because it involves several exchanges, but its structure is simple. Once you see the formation for a discovered attack, you just methodically work through all the exchanges bearing on the obstructions that prevent it from working. This example illustrates a particularly useful version of the idea: when an enemy pawn blocks a discovered attack against a piece that lies behind it, perhaps the piece you want sooner or later can be made to replace the pawn if the pawn is taken. That is what happened here: the d4 square never was emptied; rather, the pawn eventually was replaced by the target of the exercise—the queen. But to get to any of this you first have to see the basic pattern for a discovery on the d-file without being blinded by the obstacles in the way. Of course if Black sees all this coming he will simply forfeit the pawn at the beginning rather than head down the road toward larger losses by making a recapture; he will notice the kernel of a discovery for White and will realize that d4 is a square of danger. This position is a good study in the value of playing through a series of liquidations in your mind's eye. The particular type of liquidation shown here is fairly common: a pawn near the middle of the board often will be protected and defended several times, making

it important to understand what would happen if all those potential captures and recaptures were played out. Dg324: White has the makings of a discovered attack on the g-file, of course, where his rook and bishop are in the standard formation. White looks for a violent, time-consuming move he can make with the g2 bishop and finds—nothing. BxB is met by QxB with no gain; Bf3 just loses the bishop.

Dg324: White to move Still, a discovered attack pattern with a rook aimed at the enemy queen is an important opportunity, so White looks for other moves he could make that would create a target for the g2 bishop. It would be ideal if the bishop could check Black’s king. Where would it need to go to do that? To d5. What stands in the way? Black’s bishop at e4. That bishop cannot be captured, but it can be threatened with Qc2, Qd3, Qd4, or Qd5. Qd5+ is most interesting because it checks Black’s king and so requires immediate attention. Black would have to either move the king or take White’s queen. If he moves the king, White plays QxB (and if Black then plays QxQ, White has BxQ). So Black will play BxQ. Reconsider the board as it then would appear: the same potential for a discovered attack would exist, and now the White bishop’s path to d5 would not be blocked by Black’s bishop; Black’s bishop would be on d5. So White plays BxB+, and Black replies Kh8; and now White has RxQ. He has exchanged queens and won a bishop. You might also have considered starting with Qd4. It looks safer because it doesn’t expose

your queen to capture by Black’s bishop, but still attacks the bishop a second time; and it creates the threat of mate with Qxg7. But Qd4 has the major disadvantage of not giving check. A key difference between giving check and creating a mate threat is that a mate threat doesn't force such a narrow range of replies on your opponent. He may be able to address it by giving a check of his own that seizes the initiative. In this case Black can respond to Qd4 with Rxa2+. White has to reply KxR— and then comes another check from Black: Ra8. Since White has nowhere safe to move his king, he has to interpose his queen on a7 and lose it next move to RxQ. Then White has the recapture BxR, but that wasn’t exactly what he had in mind at the outset. Remember: if you resort to threats that don’t give check, you have to consider any checks (and any successions of checks) your opponent might be able to use to interrupt your plans.

Dg325: Black to move Dg325: Where does Black have the makings of a discovered attack? Actually in two places: on the c-file and on the h-file, where his knight masks his queen. Since we are focusing here on discoveries by bishops, start by working with the threat on the c-file. The rook on c8 is poised to take White’s queen if the bishop can be vacated from c5 in a forceful enough way. But where can it go? The first thing to consider is whether the unmasking piece can give check. That’s not possible here, both because the king is on a light square and because the pawn on f2 blocks the bishop’s path to the back rank. But when you see an obstruction like the f2 pawn, ask what you could do if it were gone. If the pawn weren’t there, Black could play Bg1. Does

that qualify as interesting? It should, for then the position begins to look a lot like one we saw a few frames ago; the bishop would be attacking a square adjacent to White’s king at which his queen also would be aimed. An idea thus emerges: if Black could get his queen aimed at h2 and get the f2 pawn out of the way, then Bg1 would threaten mate and be an effective discovered attack. The Black queen’s path is blocked by the Black knight on h5, but the knight can evacuate its square with check: NxB+. If White replies f2xN (the h-pawn can't be used because it's pinned), now Bg1 is possible and threatens both Qxh2# and RxQ. By the way, notice that White can reply to Bg1 with Bc4, limiting his immediate losses to a piece. White’s queen then protects h2 against a mating attack, since the White pawn and piece on the second rank suddenly are both gone. After Black plays RxBc4, White slides the queen over to e2, where it is safe and still foils the mate threat. In a later chapter we will study knight discoveries like the one that unmasked the Black queen’s attack on h2, but already you can see how the train of thought might have started there just as easily: the knight in front of Black’s queen can move out of the way with check (NxB+). Black imagines the board as it would look after the recapture f2xN, and recognizes the same sort of idea we saw earlier: his bishop can unmask an attack against White’s queen, and at the same time add a second attack on the pawn in front of White’s king by moving to g1.

Dg326: White to move

Dg326: White's bishop and queen are characteristically arranged for a discovered attack, with Black’s loose queen making a fine target on d4. Everything is prepared except a good threat for the bishop to make when it vacates the d-file. It would like to give check, naturally, but its lines to the king from b5 and g6 are blocked. What to do? When your goal is to clear a line, consider attacking pieces that are guarded by the pieces you need to move. Here the lines that White's bishop needs to give check are blocked by Black’s d7 bishop and f7 pawn. If White can capture something that one of those pieces protects, then the piece will have to move to recapture, a line will be cleared, and perhaps White can win Black’s queen with a discovery. As it happens, both of Black's blockers protect the pawn on e6, and White can take it with Rxe6+. Now if Black recaptures by any means, he opens a diagonal leading to his king, and White has a discovery that does win the Black queen on the next move—either Bb5 or Bg6. Obviously Black can capture the bishop easily either way, but you don't care; you just want to make him spend a turn that way so you can take his queen. In practice, seeing all this just gives White a way to take a Black pawn for free (and improve his position a bit), since Black would of course rather lose the pawn of e6 than his queen; if he is attentive—and you should assume he will be—he will reply to the capture by moving his king to f8, not by recapturing and setting himself up for the discovery. Many of the positions we are studying work that way. In practice they yield a payoff, but not necessarily the first and best one you say; for your opponent may see the coming disaster and choose to make some lesser sacrifice to avoid it. Dg327: Now consider how these ideas can look when you’re playing defense. The two sides are fighting for control of the center; Black would like to get rid of one of White’s central pawns. He attacks the pawn on d4 twice (with his queen and knight), and it is defended just once (by White’s knight). So should he take it with Nxd4?

Dg327: Black to move It is important to visualize such sequences and consider what would be possible on the board as it would look afterwards. Picture 1. …Nxd4, 2. NxN; QxN. The implications of the resulting position are clear if you notice the kernel for a discovered attack that White has on the d-file all along. That kernel is reason for Black to act with great care in any operations on that file; taking the d-pawn is asking for trouble, because it creates a target for White’s queen after it is unmasked. In this case the bishop on d3 would end up able to give check with Bxb5, winning Black's queen on d4 next move. So Black dares not play Nxd4 in the first place after all. Notice how those quick exchanges on d4 ended up leaving White with a new way to check Black's king and also with a great new target for his queen to take once it's unmasked. An earlier point repeats: when a contested pawn lies in the center, don't just ask who has more pressure against it. Ask what the board would look like after those pressures are spent.

3.1.8. Horizontal Discoveries. Thus far we have been considering positions based on a single root idea: a bishop masking an attack by a queen or rook on the same file. The masked piece travels vertically up the board after the bishop vacates its square. But of course bishops also can unmask attacks by pieces on the same rank—attacks that are horizontal, with the unmasked piece running sideways across the board. These are some-

what less common than vertical bishop discoveries; it is easier to arrange a vertical discovery because it's easy for a queen or rook to move from their starting positions on the back rank onto open files where bishops sit—and then to travel up the files once the bishops move out of the way. A horizontal discovery usually requires that a rook or queen get out toward the middle ranks of the board first so that it can then travel sideways productively. At any rate, the logic and mechanics here are no different than in the positions we already have studied. The main new challenge lies just in spotting a new kernel: the rook or queen alongside the bishop on the same rank, rather than behind it.

Dg329: White to move Bh6+ doesn’t work because the queen can both dissolve the check and take itself out of danger with QxB. Be5+ is better because it threatens Black’s king from a square the queen can’t reach, so the queen is lost one way or the other. If Black plays f7-f6, White replies RxQ; if Black plays Qf6, White has BxQ.

Dg328: White to move Dg328: In the example, where does White have the makings of a discovered attack? His bishop on c2 masks nothing on its file, but on the second rank it masks an attack by the White queen against Black’s rook. From here the thinking is familiar. The bishop must vacate the rank violently, and this it does with Bxh7+. After Black fends off the check with KxB, the way is clear for White to play QxR. White wins the exchange and a pawn with a simple discovered attack turned on its side.

Dg329: Find the kernel of a horizontal discovery for White. He has his rook "behind" (i.e., masked by) his bishop on the fourth rank; he has a good target for the rook in the Black queen on h4; and he has a check to give with his bishop—two of them, in fact: Bh6+ and Be5+. Which is better?

Dg330: White to move Dg330: This time the search for the basis of a discovery leads you to the first rank. Black’s queen appears to have pinned White’s bishop to his rook; but if the bishop can vacate the rank forcefully enough, White can turn the tables and play RxQ. Indeed, everything is in place for a discovered attack except a suitable threat for White’s bishop to make. It can’t now threaten Black’s king; the bishop travels on dark squares and the king is on a light one. But you see that by moving to h6 the bishop could line up behind the White queen already aimed into the king's territory. This cries out for consideration of QxR, both as a climax later and as a preliminary table-setting move now. Or you might come at the position from the other direction by just looking for checks you can use to move the king into a vulner-

able position. White has two: Qxf7 and QxR. Qxf7 still leaves the king on a light square after KxQ. But if White instead plays QxR, the recapture KxQ leaves the king on f8. Now the c1 bishop would be able to give check with Bh6+; White next plays RxQ, taking the queen and netting a rook with the sequence. Dg331: Find the kernel of a discovered attack for Black. He has the queen-behind-bishop pattern horizontally on the sixth rank. He has a target, too; he could play QxQ for free if the bishop on b6 were out of the way.

Dg331: Black to move Again we have a clear view of the problem; we need something violent and distracting for the bishop to do—probably a check, but at the moment the bishop can’t threaten White’s king, which is on a light square. We need to move the king. We even can see where: if it could be forced onto g1, Black could play BxB+ and win the queen. The methodical way to pursue this is by experimenting with checks using Black’s other pieces. There is just one to consider: Rxh2+. How would White respond? He has two legal moves: Kg1, which is what we want, or KxR, which is more likely and doesn’t immediately help us. Okay; but imagine the position after KxR; look for you next check. The only piece that would have the power to check would be the queen. Qh6+ gives check while still staying on the sixth rank and preserving the kernel of the discovery. White’s only legal move this time is Kg1, and then the discovered attack BxB+ works to win White’s queen.

Dg332: Black to move Dg332: Where does Black have the makings of a discovered attack? On the fourth rank. This pattern is easy to overlook during a game because of the pawn that lies between the Black queen and bishop. It's still important to see the kernel; teach your eyes to hop over pieces or pawns in the way of the pattern, since it may be possible to get rid of those obstructions, as is our challenge here. Black has a target in White’s queen on a4, and he has a check for the bishop in BxN+. All the ingredients are in place save one: the pawn on c4 must be removed. The usual way to clear an enemy pawn from a line you need is to capture something it protects, forcing it to move to recapture. Black does this with Nxd5. White can’t recapture with his c3 knight because it’s pinned; and if he plays c4xN, the way becomes clear for BxN+, discovering the fatal attack QxQ. Of course White should prefer just to forfeit the pawn. There remains one complexity to consider: White could reply to Nxd5 with QxB. (Don’t automatically assume that a capture will provoke a recapture; it might provoke a fresh capture by your opponent elsewhere.) Of course this would leave White’s queen open to capture by the knight now on d5, but it also would unpin the knight on c3 and thus ready it to capture Black’s queen next move. So does White’s QxB ruin Black’s plans? Not quite. Imagine it playing out: 1. …Nxd5; 2. QxB, NxQ; 3. NxQ. When considering a little sequence like this that would reposition either or both of your knights, pause to consider whether there might be a kicker at the end in the form of a knight fork. Here the exchanges just described would leave a Black knight on

b4—and able to drop next move to c2, where it forks White’s king and rook.

Dg333: Black to move Dg333: Here is a demanding position. A habitual scan for discovery kernels for Black makes the lineup on the d-file obvious, but nothing productive can be made of it because the target (the d4 knight) is secure. Less obviously, though, Black has a kernel of sorts in horizontal form on the sixth rank. There are no pieces blocking the path between queen and bishop, and the bishop has a check with Bxh2. The missing ingredient this time is a target: Black’s queen has nothing at all to attack once it is unmasked. How might Black somehow force or attract a White piece onto a6, b6, or c6? Consider Black’s other pieces and what moves they can make that might help. The rook can’t force anything useful, but now have a look at the bishop on c8. One way to attract an enemy piece onto a square is to put one of your pieces there in a manner sufficiently threatening to make your opponent capture it. Here Black can put the c8 bishop onto the sixth rank with Ba6, where it attacks White’s queen. What response could White make? Moving the queen seems out, because that would expose the rook on f1 to capture; and letting the queen be captured likewise is out. Another option would be Nb5, where White interposes a piece between his queen and Black’s bishop. But then Black has c7-c6, attacking the knight and winning a piece. (Once on b5 the knight is pinned to the queen.) That leaves White with one other reply to Ba6: capturing the bishop with QxB. But this completes the three-piece kernel of a discov-

ery on the sixth rank, setting up the board for Bxh2+—a discovered attack that takes White’s queen. Black ends up exchanging two bishops for a queen and a pawn. (Moving the queen, and enduring the loss of the exchange with BxR, would have been better after all for White.) Seeing this idea will be easier after you have studied skewers, for then your attention would be attracted from the beginning by the alignment of White’s queen and f1 rook. You imagine running a piece through them with Ba6, see that this results in QxB, and then recognize the three-piece pattern for a discovery that would result on the sixth rank. Notice what has been involved in each of the positions we recently have considered: (a) Identification of the basic kernel for a discovered attack by the bishop. (b) A precise grasp of the elements of a discovery that are in place and those that aren’t—a suitable target for the unmasking piece, a suitable target for the unmasked piece, and clear lines between all the relevant pieces. (c) Methodical thought about how any obstacle or missing element might be remedied. If the problem is that the unmasking piece lacks a good target, we consider ways of drawing the king into its range: checking the king with other pieces, sometimes repeatedly, or capturing something next to the king and thus forcing it to move to recapture. If the problem is that the unmasked piece lacks a good target, we consider ways of creating one: if there are unsuitable targets already in place, we might capture them with other pieces and invite recapture by more valuable enemy pieces; if there is no target in place, we think about putting our own pieces where we want an enemy piece to go and inviting capture of them there by making a threat. Or perhaps we can threaten an enemy piece that has limited movement and force it to jump onto the rank and file where the kernel for a discovery is in place. Finally, if the problem is that there are pieces blocking the needed lines to make the discovery work, we have methods for dealing with that as well. If the obstructing pieces are our own, we look for ways to vacate them from

their squares that are violent and timeconsuming for our opponent: checks, captures, and threats. If the obstructing pieces belong to our opponent, we may be able to capture them and cause them to be replaced by the targets themselves. Or we may be able to draw them out of the way by capturing pieces they protect, or by making threats from squares they protect.

stationary, unmasked piece. After the king avoids the check, the unmasking piece gets to make a second move—perhaps a capture or a retreat after a capture already made. This rearrangement of power between the masking and unmasking pieces makes the discovered check especially devastating, because it means that the unmasking piece in effect gets to make two consecutive moves unmolested.

That is not a complete catalogue of problems that arise in creating discoveries and options for dealing with them, but it is a summary of the most common types. You want the thought processes involved in those sorts of sequences to become second nature so that you see them right away and can spend your tactical time thinking about more complicated things: how these ideas might be combined, or combined with other tactics; and how they might come into view after a series of preliminary threats or exchanges. We will return to all of these patterns, and explore and reinforce them further, when we examine discoveries by other pieces in the following chapters.

This section starts with simple one-move discovered checks, then shows how the methods examined earlier in the chapter apply in this setting. In addition to discovered checks, we also will be looking at a few other patterns where the unmasked, stationary piece provides the distracting threat (even if not with a check) and the unmasking piece does the damage. In all cases you still are looking for the same kernel: a bishop masking a rook or queen. What’s new here is that you may need to draw the king into position to be attacked by your stationary piece rather than your mobile piece; and when you create a target for the mobile piece, you think a little differently because you have greater liberty: you look for ways to exploit the special opportunity to make two unfettered moves with the same attacker. The examples will make all this more concrete.

3.1.9. Introducing the Discovered Check. Think of how pleasant it would be if you were allowed from time to time to make two consecutive moves without interruption by your opponent. You could use the first one to bring your bishop in position to attack the enemy queen, then on the next move play BxQ. Or you could use the first move to capture a protected enemy piece, and then use the second move to retreat before being recaptured. These marvelous possibilities are realized in the form of attack known as the discovered check.

Dg334: White to move

We have seen that in a usual discovered attack the unmasking piece is sacrificed or otherwise creates a time-consuming threat — often a check — so that the unmasked piece can capture something on the next move. A discovered check reverses the pattern: the move by the bishop or other unmasking piece exposes the enemy king to a check from the

Dg334: In the skeletal position we have the idea in simplest form. White has the kernel of a discovered attack on the c-file. If the bishop moves, Black’s king is in check and will have to move, allowing the bishop to make a second move. The bishop’s target, of course, is Black’s queen. The bishop has two ways to attack it: Bg8 and Bd3. Either way the queen

is lost. If Black moves his king, White plays BxQ; if (in reply to Bg8) Black plays Qc2, White has RxQ.

It’s a light-squared bishop, so look for a threat against something on a light square. The choice target turns out to be Black’s bishop on b7, because it's loose; if White can reach it in two moves he will take it for free. White thus plays Ba6+. After Black fends off the rook check, BxB wins the piece.

Dg335: Black to move Dg335: The kernel of the discovered attack for Black on the f-file should be evident enough. It also should be plain that this is a setup for a discovered check. Black can exploit the pattern by plotting a two-move course for his bishop. Look for White pieces that, like the bishop, are on dark squares. The queen always is a preferred target. Bd4+ attacks it, and BxQ takes it a move later after White moves his king out of check.

Dg337: Black to move Dg337: Notice the kernel of a discovered attack for Black: the bishop in front of the rook on the f-file. If the bishop moves, the rook attacks White's king; that makes this a case of discovered check, giving the bishop two moves to make trouble. It’s a light-squared bishop, so look for a good White piece on a light-colored square that it could attack—and find the queen. The bishop needs to attack it in one move and take it with the next. The answer thus is Bxc2, again winning the queen either by BxQ, or (if the queen moves to block the check—an important possibility to remember) with RxQ.

Dg336: White to move Dg336: You first see the bishop-in-front-ofrook pattern on the e-file, and then that once the bishop moves Black will find himself in check. This means the bishop in effect can have a free move, because after it moves once—and almost regardless of where it goes—Black will have to address the threat against his king by moving it or interposing something in front of it. So think about where the bishop could go on its next move that would allow it to inflict damage a move later.

Dg338: White to move Dg338: Here the kernel is on the h-file; if the bishop moves, White’s queen gives check and Black’s king has to move. What to do with the bishop? It travels on the dark squares, and

the only Black piece on a dark square is the queen, which the bishop can’t reach in two moves. But wait: think more carefully about the first part of the attack—the part against the king. Where would the king go? Its only escape would be to g7. If White could attack that square with his bishop, the king would have no place to go. So Bf8 is mate: a case of discovered checkmate. The important lesson is that when you think of where you might move the unmasking piece, don’t overlook pressure it can exert against squares, and especially against squares next to the enemy king.

3.1.10. Removing Impediments to Discovered Checks. We have seen how to deal with obstacles that may stand in the way of a normal discovered attack—how to create good targets for each piece, and how to open blocked lines. The same methods come in handy when building discovered checks, so there is no need to rehearse them here in detail; but since their use here sometimes looks a little different, a few examples may be useful. First, discovered checks often have to be created by making a threat or sacrifice that brings the king within range of the stationary piece. And since an unmasking bishop can go after enemy pieces that sit on the same color squares where it travels, you sometimes have to force a target onto one of those squares.

Dg339: Black to move Dg339: In the frame, Black has the kernel of a discovered attack on the g-file: the rook be-

hind the bishop. If Black unmasks the rook it will attack the pawn at g2, adjacent to White's king; if the king were moved over a square, Black would have a far more potent possibility: a discovered check. How to move the king? Look for other pieces Black can use to check it, capture pieces next to it, or both. There is one option: Qxg2+. White’s only legal reply is KxQ. Now that the king has been lured onto the g-file, all that remains is to find a good target for the unmasking piece—the bishop on g7. It travels on dark squares. White’s queen is on a dark square. So Bxe5+ takes a bishop, puts White’s king in check, and wins back White’s queen after Black’s next move. By the way, if you have studied the chapter on bishop forks, another idea for Black should cry out for attention here as well: BxB+, forking White's king and queen. What makes it especially interesting is that if White takes the bishop, Black then appears to have mate: Qxg2#, with cover provided by the rook on g8. Indeed, Black seems ready to mate soon no matter how White replies to BxB. But not quite; for the surprising actual result of Black's bishop fork is that it permits White to mate! The point to notice is that when White replies to the fork with QxB on e5, he checks Black's king and seizes the initiative. Black has to play Rg7 to block the check. Then White plays Rg3; this not only blocks Black's mate threat against g2, but allows White to mate a moment later on g7 with QxR. There is nothing Black can do to stop it; his queen is too far out of position to help. The moral: you must be especially careful to observe whether any of your opponent's replies to your ideas will put you in check. It can ruin everything.

Dg340: White has the kernel of a discovery on the c-file, but it's not yet in working order. The rook on c1, if unmasked, has nothing but a protected rook as a target, and the unmasking bishop likewise is unable to threaten anything more valuable than itself.

Dg340: White to move

Dg341: White to move

But with the kernel in place, think hard about what it would take to make it succeed. Try saying “if only…” If only Black’s king were on the c file, White would have a discovered check and could take Black’s loose bishop with two moves. So now think about ways to move the king by attacking it with other pieces. The only useful piece for the purpose is White’s rook on d2. Can it give check? Yes, with Rd7+. Examine the move. Critically, it’s a fork of Black’s king and his loose bishop; if Black moves his king, he loses a piece. His only way to stop the check and also protect the bishop is by moving his rook onto the seventh rank: Rc7. Now what checks would White have, and with what results? RxR+, leading to KxR; and then—aha!—the king has been drawn onto the c-file. White unmasks a discovered check with Bf8+, winning the bishop on g8 after Black's king moves.

Dg341: Here is a small study in how the threat of a discovery can influence other matters on the board. White has the makings of a discovered attack on the e-file. What could the rook on e1 attack if the bishop in front of it were moved? Just the pawn on e6. But notice that behind that pawn lies Black’s king. It’s another “if only” point: if only the pawn on e6 were gone, White would have a discovered check with Ba6+, winning the queen after Black moves his king. This means that the Black pawn on e6 in effect is pinned in place. White is free to play d4-d5 if he wishes; if Black captures with e6xd5, White replies with his discovered check. So if he is alert Black will instead reply with a move like Bd6 (preparing to castle) and allow White to play d5xe6 next move, planning to respond with f7xe6—but now Black’s position for castling is not quite so strong. Indeed, notice that Black’s position overall is rather poor. He is behind in development (too many pieces still on their original squares), and he has weak light-colored squares on his queenside (“weak” in the sense that White can put pieces on them and Black can’t chase them away with pawns)—made worse by the fact that Black’s light-colored bishop, which he might have used to protect those squares, is off the board, while White’s still is available.

You could have seen all this as well by noticing that the bishop on g7 is loose and thus an important target. You look for forks that would attack it and find one in Rd7+; you imagine the reply Rc7 from Black; this invites an exchange of rooks on c7; put this together with the kernel of the discovery on the c-file and you are led back to the g7 bishop as a target—but this time as the target of a discovery rather than a fork. Please excuse the absence of the White king from g1. He's having a break.

In any event, the general point of the study is just to see how the possibility of a discovered check in the background can influence other features of the game. The threat of it can paralyze those pieces that prevent its execution and so permit advances that would not otherwise be feasible. Here it ultimately causes

Black to end up with an isolated pawn and bad castling position.

3.1.11. The Bishop and Rook Mate. Since we have been considering positions where a bishop unmasks check by a rook or queen, let's look at one especially important application in detail. The unmasking bishop need not always go hunting for an enemy piece to capture; it also may be able to move to a diagonal where it can contribute to checkmate. The key mating pattern we will examine is this: a rook attacks the enemy king along its file, with a bishop (a) providing protection for the rook, and often (b) helping to seal off the king’s flight squares. Here we will look at some examples of how the pattern looks in practice.

Dg343: White to move Dg343: Where does White have the kernel of a discovered attack? On the g-file. You look for a target for the rook once it is unmasked and find none. If only the king could be drawn onto the g-file, you think; and so you look for ways to make it happen. What checks are available? Qg8+. Black’s only legal reply is KxQ, moving his king onto the sensitive line. Now if White moves his bishop he gives check with his rook, so the question is what move to make with the bishop. It had better be good, since White sacrificed his queen to get here. A combined attack against the king is indicated; Be6++ checks the king with both bishop and rook. Black’s only move is to retreat the king to h8. Now comes mate: Rg8#, with the rook attacking the king and its only flight square, and getting cover from the bishop.

Dg342: Black to move Dg342: In the position Black has the makings of a discovered check on the f-file. He can go looking for White pieces to take with his bishop, but the better plan is to move the bishop to a diagonal where it, too, can be brought to bear against White’s king. Hence Bd3++—a case of double check where two of Black’s pieces attack White's king at the same time. In response to a double check the only legal reply is to move the king. Here it must go to e1. Now comes the classic mate: Rf1#. See how the rook makes the first rank and the f-file impossible places for the king to be, while the bishop on d3 (a) protects the rook and (b) closes off the king’s other possible flight square, e2.

Dg344: Black to move Dg344: Black has the kernel of a discovered attack on the f-file. The potential target for his rook is White’s rook on f1—which is protected, however, by the enemy king. Black’s queen is trained on the rook already, so the solution is an exchange: Black plays QxR+, requiring the reply KxQ. Now the king is on

the f-file, so when Black moves his bishop he has a discovered check. But instead of looking for White pieces to attack with the bishop, think first about ways to give check with it— i.e., double check—and go for mate. Bd3++ forces the king to move. This time it can go two ways: back to g1 or on to e1. Either way Black executes the now-familiar mate pattern with Rf1#. Dg346: Black to move

Dg345: White to move Dg345: White has the kernel of a discovered attack on the d-file, where the bishop masks the rook. What prevents this from being an effective discovered attack, or indeed a discovered check? First, White’s own queen blocks the rook’s path up the file; second, there is not yet a Black target on the file. The solution to these problems becomes clear enough when they are viewed together: use the queen to bring the king into range. Thus Qd8+ forces KxQ. Since White will have sacrificed his queen, he will be interested in mate; can he get it? Bg5++ gives check with both bishop and rook; Black must move his king. He can take it two places: back to e8 or to c7. If he plays Ke8, White follows with Rd8#, using our current pattern. If Black plays Kc7, look for White’s next check: he plays Bd8#, using something like the reverse of the current pattern. The bishop attacks the king and cuts off the flight squares on its diagonal; the rook protects the bishop and cuts off the Black king’s remaining flight squares. (White could have made a different second move, of course: Ba5+, giving the double check from the other side of the board. But it doesn't work; Black's king soon can escape to e6.)

Dg346: Black’s queen is about to get taken by the rook on d4, so it would be natural to think about moving it to safety; but Black can do better. Think about offense and notice the kernel of a discovery on the e-file. What target would the rook have if it were unmasked? It would be aimed at White’s king, and the check could be made a double with Bb4—if only the White pawn on e3 weren’t in the way. With the obstacle identified, be methodical in getting rid of it. Try capturing something the pawn protects. It guards the rook on d4, which Black can take with QxR. Now if White replies e3xQ the e-file has been opened for the double check Bb4++. White then has to move his king to d1, permitting Black to execute the standard mate: Re1#, cutting off the king’s flight squares on the first rank and on the e-file while the bishop protects the rook and cuts off d2.

Dg347: White to move Dg347: Now let us tilt the pattern we are studying on its side. White has the makings of a discovered attack on the h-file, where his bishop masks his queen. Naturally you experiment with moves that take the bishop out of the way and allow the queen to give check.

But before getting too far into the bishop's possibilities, ask what the king would do once checked and whether the bishop might aid in the creation of a mating net. The king is stuck on the side of the board and so could only be moved to g7. The bishop might cut off this possibility with Bf8+. So then what would Black do? Since moving the king would be impossible, he would interpose his bishop on h5. This way if White plays QxB he loses the queen to g6xQ. Don’t give up, though; always ask what checks would have become possible at the end of the sequence you are considering. Here the answer lies in White’s d6 rook that also is trained on the same sector. Imagine 1. Bf8+, Bh5; 2. QxB+, g6xQ, and now notice that with the g6 pawn moved out of the way, White has a fresh check to offer: Rh6—mate! The rook and bishop operate the same way here as they have in the previous examples; the only difference is that they do it on the side of the board rather than along the top or bottom. The keys to the position are, first, to be aggressive in imagining 2. QxB, even though on its face it looks suicidal; and, second, to consider how your rook can get in on the act. Once your mind becomes focused on a pattern, such as the business here with queen and bishop, it it easy to forget how your other pieces might be able to rush in and assist once the board has changed a little. Many a sequence is salvaged and then made crushing by adding new, unexpected firepower after the pieces which first start the combination are spent.

while the mobile, unmasking piece remains free to make two attacking moves.

Dg348: White to move Dg348: In this first position, White’s bishop and rook are in the natural position for a discovery. The rook is aimed at Black’s queen, a threat so powerful that unmasking the rook works much like a discovered check: White will get to make two unfettered moves with his bishop while Black saves his queen. White doesn't quite have the same flexibility in attacking the queen that he would have with a discovered check, because unlike a king the queen sometimes can move out of harm’s way and guard against whatever threat the mobile piece has made. But that doesn't spoil White’s possibilities here. He looks for a two-move attack he can launch with his light-squared bishop, and sees that Black’s rook is loose and lies on a light-colored square. Ba6 thus attacks the rook on move one and wins it on move two (unless Black plays QxRe1, preferring to lose a queen for a rook rather than losing a rook outright).

3.1.12. Other Large Threats By the Stationary Piece. The logic of the discovered check sometimes can arise in positions where the unmasked piece doesn't give check but makes a different threat—perhaps a threat of mate, or a threat against the queen—that nevertheless is so powerful that it must be addressed; mean-

Dg349: Black to move

Dg349: One way to start a tactical assessment is by just considering what each of your pieces can do. This includes an automatic glance not only at the diagonals where your bishops sit but also at their ranks and files to see if they contain allied pieces that might be able to deliver discovered attacks. Here Black's bishop on d7 hides the rook on d8 with nothing otherwise blocking the rook’s path to White’s queen. The setup is perfect for a discovery—not quite a discovered check, but an attack based on the same model where the unmasked piece creates a distraction that the enemy must address while the unmasking piece is given two moves to inflict harm. So Black looks for violent moves to make with his bishop and thus finds BxN. Since White will be confronted with a threat to his queen, he won’t be able to recapture with e4xB; Black therefore will be able to withdraw his bishop to safety on his next move and will have gained a piece.

from White’s stationary piece, so White’s bishop—the unmasking piece—will get a free second move. White thus plays Bd5, attacking the queen. Indeed, follow the possible resulting moves and you find that White need not be satisfied with the queen; mate soon follows no matter what Black does. If Black plays QxBd5, for example, he might seem to have created a defense against mate: if White plays RxR+, Black can play Qg8, blocking the check—yet then White mates with RxQ. If Black instead tries to extinguish the mate threat by replying to Bd5 with RxRf2, White can skip BxQ and just go straight for Black’s king with Qg8#; the queen gets cover from the bishop on d5. Black's "best" reply to Bd5 (it hardly matters) is Rd6-f6; all this does is throw a blocker onto the f-file. White's rook plows through it and Black soon runs out of stalling maneuvers.

Dg351: Black to move Dg350: White to move Dg350: Here’s a variation on the current idea. Where does White have the kernel of a discovered attack? On the f-file. (The f7 bishop and f2 rook are separated more than is usual, but it’s no less important to see their relationship.) Having found the kernel, ask what the rook could do if the bishop were out of the way. It could attack Black’s rook on f8. That’s something, but on inspection of Black’s king there is more: the king has no flight squares and not many guards; so if White could play RxR it would be mate. This means that if the bishop vacates f7 it creates a discovered mating threat in RxR that functions like a discovered check: Black will have no choice but to fend off the threat to his king

Dg351: The crucial square to focus on this time is g2. Black has a knight already attacking it, and his queen is aimed the same way; if he could get his queen onto g2, it would be mate. The queen’s path to g2 is blocked by his bishop. He could try attacking g2 by first moving his queen to c6, but this gives White a move he can use to defend g2 with Qg3. So focus instead on the g-file, where Black has the kernel of a discovery. If the bishop were gone the queen would threaten to mate, so Black looks for mischief he might make with his bishop—or, better, some way it might help with the queen's landing on g2. He finds no checks or captures for the bishop but identifies a move that nevertheless is effective: Be3, which attacks the bishop on f2 and pins

it to White’s king; it also cuts off the path of the White queen along the third rank toward any possible defense of the g2 square. White is doomed: (a) If he captures Black’s bishop with his own, his queen remains blocked; Black mates with Qxg2. (b) If White instead uses his queen to take Black’s bishop, he likewise is mated immediately by Qxg2. (c) If White advances his g-pawn to g3, Black plays Qxg3+ and mates a move later. (d) If White advances his g-pawn to g4, he effectively blocks the descent of Black’s queen down the g-file, but Black plays Qc6 and again mates soon on g2; for the third rank still is impassable to White’s queen.

Dg352: White to move Dg352: This is a rich, difficult position that will reward some study time. Presumably you see that White has the kernel of a discovery on the f-file. You also see a natural way to execute it: 1. Bc7, attacking Black’s queen and also threatening 2. Qxf7+. But you wonder how formidable the latter threat really is. Suppose Black replies to 1. Bc7 with 1. ... QxB, allowing White to carry out Qxf7. Now Black’s king is forced to h8—and then what? Your queen can do no more by itself from f7. The key move to see is 3. Rh4—a fresh mate threat (Rxh7#) against Black’s king on its new square. Black has a move he can spend responding to it but there is nothing he can do to avoid trouble. He can’t get any of his pieces to h7 to defend the square. The most he

can do is advance his h-pawn. The first possibility, 3. ...h7-h6, doesn’t help: it results in 4. Rxh6+, BxR; 5. Qh7#. Black's second option, 3. ...h7-h5, is a little better as it avoids mate. Play goes 4. Rxh5+, g6xR; 5. Qxh5+ (always looking for the next check), Kg8; 6. Qh7+, Kf8; 7. Ne6+ (forking Black’s king and queen). The net: White gives up a bishop and a rook to gain a queen, three pawns, and a better game (his offensive continues; there are various ways he might win still more material). Assuming you follow all this (it's worth a patient look), what does it prove? Just that if Black replies to 1. Bc7 by playing QxB, he gets hurt; so Bc7 does indeed give White a working discovered attack. But what will Black do about it? Obviously he doesn’t want to simply forfeit his queen; does he have anything better? Ideally he would like a move that makes a good counter-threat against White while also defending against mate. Black almost has such an option in 1. ...Ne5, attacking White’s queen and guarding f7. Of course it loses the piece to BxN, but it’s still Black’s best reply. This position contains a couple of natural “stuck points”—places in the analysis where it’s easy to hit a wall. The first comes after you see 1. Bc7, QxB; 2. Qxf7+, Kh8—and now it needs to occur to you to bring the rook over to h4, which is tricky to see for several reasons: (a) Rh4 brings a piece into the action that had not initially appeared to be part of the plan. It’s natural when you begin playing with a tactical idea to focus on the principal pieces involved—here, White’s queen, bishop and knight. But as we recently had occasion to note, many a sequence turns out to depend precisely on the clever addition of an unexpected piece or pawn to the attack. This is a key reason why developing your pieces (i.e., getting them off of their original squares) is important before launching an offensive. They all may have the potential to perform supporting roles. The repeating moral: think about all of your pieces and how they can help when planning a tactical sequence.

(b) Rh4 requires you to remember that the bishop now on f4 would be gone after the first move and that this would open a line for your rook to use to reach the h-file. This is a standard sort of cognitive challenge at the chessboard. The only cure is to be careful about it when you practice visualizing these sequences: every time you make a move, think not only of the piece on its new square but also of its absence from the old one. (c) Rh4 is not a forcing move in the strong sense associated with a check or capture, so it might not spring to mind as quickly as those other possibilities would. But it still requires a look because it creates a mate threat: it aims a piece at a square next to the enemy king that you already have under attack. It therefore forces Black’s reply; it make him advance his h-pawn, which ends up having other consequences as well. Moves of your heavy pieces (your queen or rooks) to the h-file against the castled enemy king are common sources of good, forcing threats. A second natural stuck point comes after 3. Rh4, h7-h5; 4. Rxh5, g6xR; 5. Qxh5, Kg8; 6. Qh7+, Kf8. At this point you need to see 7. Ne6+—the knight fork. You might overlook it by thinking in a rut. You have been trying to chase down Black’s king with your queen; now you have run out of ways to do it. The earlier point repeats: when your idea hits a wall, remember to ask afresh how your other pieces might help, and whether some new tactical idea might make an unexpected appearance. This is especially important when you have a knight in the vicinity and the enemy king is moving; the potential for a knight fork may pop up at any time during a sequence. (And of course you have to remember as well that at this late stage of the sequences Black's queen still sits on c7, where it went on Black's first move.)

3.1.13. Horizontal Discovered Checks. Naturally a discovered check can occur horizontally along a rank as well as vertically

along a file. Here are a few examples of what the horizontal patterns look like.

Dg353: White to move Dg353: In the diagram White has the makings of a horizontal discovered check on the eighth rank. The Black king is in place; the only question is what the bishop should do to take advantage of the check that will occur once it moves out of the rook’s way. It could take Black’s knight, of course, with Be7+, but it would be a mistake to settle for so little. Consider first the king’s response to the discovered check; ask whether the unmasking piece might add to a mating net. In this case the king would be forced to move to g7. Can White’s bishop attack that square when it unmasks the rook? Yes: 1. Bf6# is mate.

Dg354: White to move Dg354: Where does White have the kernel of a discovered attack? Not on any file, of course, but along the sixth rank. It isn't easy to see because at present the rook has no target once unmasked; but White would have a discovered check if Black’s king could be drawn onto h6. Experiment with any checks White can give using other pieces—or pawns.

Here h5-h6+ checks the king; it also puts a pawn on the square where we want Black’s king to go, inviting a capture there. Black has two options: take the pawn or move the king to the back rank. If he goes the latter route, consider first what checks would be possible and you find Re8—which is checkmate. (See how the pawn on h6 and the bishop on g6 together seal off all the king's flight squares on the seventh rank.) So instead Black will have to play 1. ...Kxh6. But now he has put his king on the same line with White’s bishop and rook and has made it prey to a discovered check. White merely needs to find something good for his bishop to spend two moves doing, and he finds it in Be8+. After Black moves his king out of check, White plays BxR, winning the rook. Realistically, the most likely way you would see the tactical idea here is to start by examining the h5-h6 check as a matter of course; then you see that after Kxh6 you have a discovered check arranged—and that if the king instead retreats you have mate.

Dg355: White to move Dg355: Where does White have the makings of a discovered attack? On the third rank, where the bishop masks the queen. Well, in practice you probably would not think quite like that, since the queen so plainly has no target on its rank if the bishop moves out of the way. The real key to seeing what can be done here is to examine Black’s king and its vulnerabilities. It is stuck in the corner; White’s bishop on b3 covers g8. And the file leading to the king is open. The king’s lack of pawn cover and constricted movement cry out

for an attack along the h-file; if White could get one of his heavy pieces (the queen or a rook) onto h3, it would be mate. Therein lies the winning idea, for White’s queen already is aimed at h3. If the bishop moves out of the way, White’s threat against that square thus is a mate threat, and requires a response from Black just as a check would. So now all White needs is a dark-squared target that his bishop can reach in two moves. The queen is the target of choice; Bxb6 wins it after Black plays Nf8 (preparing to fend off the mating threat with his knight).

Dg356: White to move Dg356: The kernel of the discovery here should be obvious enough: White is poised to give check on the seventh rank by moving the bishop out of the rook’s way. He needs a good target for the bishop. It’s on a light square; what Black pieces are on light squares? None. But that is no reason to give up. White’s task is clear: get a Black piece onto a light square—probably by forcing one of them to move there with a threat. Pawns are best for this purpose, since in the face of a pawn threat a piece usually must move; the threat can't be dealt with by just adding protection to the piece. A threat against a knight is especially useful here because every time a knight moves it switches to a different colored square. So b3-b4 forces the knight to move, and wherever it goes it gets taken—either right away by White’s bishop or rook, or (if the knight moves to c6) by the discovered check Bd5+. After Black moves his king, BxN then takes the piece, which is defended by Black’s rook but also attacked a second time by White’s rook.

3.1.14. Two-steppers: Building the Kernel. The first step in our usual studies of the discovered attack has been to find the kernel of it and build from there. But what if the kernel doesn't yet exist? Then a bit more imagination is required: you need to experiment with moves — here, moves by bishops and the pieces they can mask—that create kernels; you learn to notice when a move or exchange you might make will bring the kernel of a discovery into existence. Here are some illustrations.

Dg357: White to move Dg357: In the study White sees that he has a rook on the open e-file. He has a bishop that can reach the same file with Be7, masking the rook. Look at the position of the bishop and rook here; see how they thus are one move away from being in the classic formation for a discovery. The question is whether the move that creates the kernel also forces a target into place. Here the bishop’s move to e7 would threaten Black’s rook on f8. Black’s reply would be forced and thus easy to foresee: the rook would have to move to e8. This little sequence would create a working discovered attack: a masked piece, a masking piece, and a target all along the e-file. Now the bishop just needs a good place to go next. Bb4 threatens Black’s queen; if the queen defends itself in any way, White plays RxR#. So the queen must be lost. Notice how easy this position would be if it started with the kernel intact (i.e., with 1. Be7, Re8 already played). The challenge is just to think of White moving his bishop in front of his rook and to carefully consider the result.

Dg358: Black to move Dg358: Black faces the threat of mate with RxR, so if he’s going to take the offensive elsewhere he will need to work with checks that force White to play defense. The checks he can give with his queen—Qxh2, Qf1, or moves to the g-file—don’t quite work; but how about 1. …Bxh2+? White’s only legal reply is 2. Kh1, retreating into the corner. But now the full kernel of a discovered check has been completed: Black’s queen is behind his bishop and aimed at White’s king. This almost enables a mating sequence with 2. …Bg3+ 3. Kg1, Qh2+ 3. Kf1, Qxf2#. That last move won’t succeed here because of White’s knight on d1, however, so Black needs something else for his bishop to do as it clears the h-file and discovers check. It can’t attack anything; it’s on a dark square and all of White’s pieces are all on light squares. But consider whether it usefully might block any lines. With 2. …Be5, Black severs the protection White’s queen had provided to the rook on e8. Again White must move his king to g1; and now Black plays RxR.

Dg359: White to move Dg359: Start by examining every check. White has two: Rh8, which loses the rook

without a good follow-up, and Bh7, which checks the king and (since the bishop is protected against capture) requires the king to retreat to h8. And now—aha!—we have the kernel of a discovered check: White’s bishop masks the path of his rook toward Black’s king. So where should he move the bishop? It has no good Black targets on light squares, but the more important possibility to consider is that the bishop might help finish Black's king. The best piece to involve as a help toward that end is his queen. White would mate if it could be placed on h7; and what keeps it from being placed there is the presence of White’s own bishop on the needed diagonal. So we remove the bishop from the line with 2. Bg8+. Black has to move his king out of check with KxB or Bh6; either way, White has Qh7#. (The queen takes protection either from the rook on h1 or the bishop on g8, depending where Black's king moved.)

Dg360: Black to move Dg360: Now a defensive use of our current idea, and in a horizontal setting. Black is ahead a piece. He has to address the threat against his knight now made by White’s king. How? With offense: Black has a bishop on the eighth rank and can move his queen behind it with Qd8. That move creates the kernel of a discovered attack against White's queen. To make the threat really interesting the bishop would need somewhere good to go. Can it reach White’s king? Not quite; it can move to a6, though, at which point it is aimed at—the threatened knight. Now the defensive idea comes together: if Black plays Qd8 and White then plays KxN, as he now threatens to do, Black would be able to win the queen with Ba6+. Odd as it may seem, by

moving his queen to d8 Black thus defends his knight on e2: he creates a discovered attack that will be unleashed if his knight is taken.

Dg361: Black to move Dg361: Again White’s king can take Black’s knight on e2. Black has a bigger problem, too, for White threatens to mate by playing Qf7+, forcing Black’s king to h8 and then mating on f8 (his queen goes there and gets taken by Black’s rook; then White has RxR#). Yet Black can address both problems with the ingenious Qe8. See what this does: now Black’s queen is on the e-file, ready to defend the knight once his bishop on e5 has moved out of the way. In other words, the kernel of a discovery has been created expressly to protect a fellow piece at the other end of it. Indeed, this does better than protect the knight and defend f7 against mate. It means that if White plays KxN, Black then has a discovered check with Bb8+, attacking White’s queen as well as his king. We aren’t finished; don't forget to consider what White would do about the check you are imagining when Black moves his bishop out of the way. White could interpose his rook with Re3, not only blocking the check but attacking Black’s queen. So then what? Black looks for another check that would then be possible; so long as he keeps White busy with checks, the capture BxQ will still be waiting for him afterwards. Here Black’s next check is Qb5+. White again can interpose the rook, but this time it only blocks the check; it can pose no threat against a queen attacking along a diagonal. Now it's safe for Black’s bishop to take White’s queen.

3.2. Rook Discoveries.

3.2.1. Introduction; Simple Cases.

Dg362: White to move Dg362: You might start this one by observing that White's f5 bishop can give check with Bx h7. By itself this doesn't achieve anything, but it's something to know as you think through your options. Okay, now look at your other forcing moves — your possible captures — and what they do. There is 1. NxN, inviting Black to retake with QxN. The interesting thing about this exchange is that it puts Black's queen on a line with the White bishop, which we know can give check. Maybe now you begin thinking about slipping White's queen onto h5 to create the structure of a discovered attack on the fifth rank; you wonder how you might do it in a violent manner that forces Black's reply and keeps the discovery intact. Or maybe you just keep looking for other captures you can make. Either way you come to inspect 2. Bxg7. Black has to reply BxB or else lose the rook on f8. But after Black plays BxB the way is clear for White to play 3. Qh5, threatening mate with Qxh7. The mate threat is easy for Black to defang, of course, with h7-h6, but it serves its purpose: White gets his queen onto line with his bishop and with Black's queen, and Black has had no time to fend off the discovered attack that now has been set up on the fifth rank. White pulls the trigger with 4. Bh7+, requiring Black to play KxB and unmasking 5. QxQ. White wins Black’s queen and pawn in return for his two bishops.

We turn now to a different pattern: the rook that blocks and then unmasks an attack along a diagonal by a bishop or queen. In a way the pattern is the reverse of a bishop discovery; this time the unmasker moves vertically or horizontally while the attacker runs on a diagonal. Since the mechanics involved are familiar, we won't spend quite as much time on the rook as we did on the bishop or as we will on the knight. Still, there are some differences between the patterns that are worth a few moments of special attention and visual absorbtion. First, an unmasking rook usually has a harder time giving check than an unmasking bishop does. The bishop can act as a dive bomber, coming in on a diagonal to attack the king from above or below; the rook has to deliver check by moving straight down onto the king’s rank, or (less often) over onto the king’s file. Either of these moves can unmask an attack, as we shall see, but they are less common than the bishop’s strike against, say, h7. The significance of this is that when the rook discovers an attack, the distraction it creates more often is not a check but instead is some sort of mating threat, typically against the back rank. And discovered checks—i.e., moves where the piece behind the rook gives the check, rather than the rook itself—also make up a relatively large share of rook discoveries. Finally, discoveries by the rook also look different than discoveries by the bishop. The rook kernel isn’t as easy for the untrained eye to see as the bishop kernel; the eye is accustomed to looking up and down the files but not so accustomed to scanning the diagonals in the same way. The positions in this chapter are meant to build that visual habit. Dg363: Let’s begin with positions that are comparable to the first studies in the chapter on bishop discoveries. There, a bishop masked a queen or rook that was ready to attack an enemy piece along a file; here, a rook

masks a bishop or queen that is prepared to attack an enemy piece along a diagonal.

lar to the last one and is offered mostly for the sake of pattern reinforcement. They differ in trivial respects: the White pieces comprising the kernel of the discovery are another square apart, and this time it’s the queen rather than the bishop that is unmasked. But the execution is about the same. Black’s queen starts out as a bad target because it has protection from the knight on g7. White can eliminate the guard while unmasking the queen—and can do it with check: RxN+. After KxR, White plays QxQ and wins a queen and a knight for a rook.

Dg363: White to move There, the bishop unmasked the attacking piece with a diagonal move that checked the enemy king; here, the rook unmasks the attacker with a “vertical” move—a move down a file—that checks the enemy king. In either case, the unmasked piece has time to make its capture after the check is fended off. Where does White have the makings of a discovered attack in this first example to the left? The answer presents a new pattern: it’s on the diagonal f1-h3, where the rook masks an attack by the bishop against Black’s queen. The questions about the idea's execution are familiar: what violent move can the rook make that will require a time-consuming response from Black, giving the bishop time to take Black’s queen? The answer, of course, is a check: Rxg7+ requires Black to play KxR (or move his king); and now White plays BxQ.

Dg365: White to move Dg365: The general idea here is the same as before: see the queen-behind-rook pattern for White, this time running in the other direction; notice the Black queen, poised to be taken by White’s queen if the rook can move out of the way with check. Here the rook’s check probably is of its most common type: the move to the back rank, in this case with Re8+. The check easily is defused with RxR, but then White wins the queen with QxQ.

Dg364: White to move Dg366: Black to move Dg364: Where does White have the makings of a discovered attack? This position is simi-

Dg366: Where does Black have the makings of a discovered attack? There is nothing on

the files or ranks, but along the g1-a7 diagonal Black has a bishop masked by a rook. Does the bishop have a suitable target if the rook moves? Yes, in White’s unprotected knight. As discussed in more detail in our work on forks, an unprotected or “loose” piece always calls for a look at whether it can be taken with a tactical maneuver. Here the question is whether Black can vacate his rook from c5 in a manner that is time-consuming enough to allow him to take the knight a move later—and that doesn’t lose the rook. (Since the payoff of the discovery is just going to be a knight, Black can’t afford to sacrifice his rook the way he did in the previous positions.) So Black looks for safe rook checks and finds Rc1+, where the rook is covered by Black’s bishop at e3. The move forces the king to move to a2 and then allows Black to play BxN safely.

what large threat can White create with the rook?

3.2.2. Threatening Mate.

Now notice that if it were Black’s turn to move he would have Qa1+. White would be forced to reply KxQ—after which Black has the knight fork NxB, winning a piece. This should worry you a little for the reason sketched a couple of paragraphs above. The first move in White’s planned sequence (Rxf6) is a capture and mate threat, but not a check; so you have to consider whether he can give checks of his own that will derail your plans. In this case Black could respond to Rxf6 with two consecutive checks, as just discussed: Qa1+, and then NxB+, forcing White to move his king. So are White's plans foiled? No; for then Black is out of checks that hold the initiative: the next move he wants to play is NxQ, but he can’t afford it because Black mates with RxR. White thus holds onto the queen.

In the positions just seen, the attacking player used his rook to give check. The opponent’s need to defend against the check gave the piece that had been uncovered by the rook time to win material on the next move. Sometimes the rook can achieve much the same effect by threatening mate, as this puts the enemy under pressure similar to that created by a check. A rook most commonly can threaten mate by offering to drop onto the back rank when the enemy king is trapped there. This theme is worth our independent attention for two reasons. First, seeing a mate threat often is harder than seeing a check; it takes some practice. Second, when you work with mate threats you have to be especially careful to consider what trouble your opponent can make in reply. Since by assumption you haven't put him in check, you may have left him with latitude to respond with checks of his own that seize the initiative. Dg367: In the current position White has the kernel of a discovered attack along the g1-a7 diagonal, where his rook masks his queen— which otherwise would be able to take Black’s queen. Now think about execution:

Dg367: White to move Rxf6 is its only capture, but the move is more than that: it aims the rook at f8, where it would mate the trapped Black king with RxR#. So in reply to 1. Rxf6 Black has to capture White’s rook, which of course creates time for White to play QxQ on his next move.

Dg368: A similar idea. First find where White has the makings of a discovered attack. The kernel lies on the long a1-h8 diagonal, where White’s rook masks his queen in familiar fashion. Look for a target for the queen once it’s unmasked and see that Black’s queen is in the line of fire—and that it's loose.

Dg368: White to move

Dg369: Black to move

The challenge now is straightforward: vacate the rook from d4 in a way that compels a response from Black. The rook has no checks, so examine the Black king’s position for vulnerabilities. It is trapped on the back rank; although it isn’t entirely sealed in by its pawns, White’s bishop closes off the flight square on g7. The same idea we saw in the previous position thus works here. An attack by White’s rook against Black’s rook on e8 would be a mating threat, because if White can play RxR the game ends. White makes the threat with Re4. Black has to eliminate White’s rook to stay in the game. He has two ways to do it. The first is BxR, to which White replies QxQ and mates soon. Black also has the option of replying to Re4 with RxR. How should White reply?

On the long a8-h1 diagonal. As usual the rook masks the queen, and if it were moved Black could play QxQ. The important question involves what to do with the rook. Again it has no checks, so consider the White king and its vulnerabilities. Here as in the previous position it is stuck on the back rank, as Black’s bishop on h3 cuts off its escape. And once more the king has a single guard: the rook on e1. If Black threatens that rook with his own, he threatens mate. So he has two possibilities, either of which works: 1. …Rd1 or 1. …Re5.

This time the answer for White isn't quite QxQ, since Black then uses his rook to mate on e1. White instead needs to work with checks to prevent that possibility. By moving his rook off the back rank, Black has made this easy: White plays Qc8+, which requires Black to interpose his queen on d8. White takes it (QxQ+); then we go through the same process with Black's rook; then it's mate.

There is a little more to say, because you always must ask whether your opponent has a way to both move the targeted piece out of danger and spoil the mating threat. White's queen can't move to the east because Black then threatens to mate with Qg2. But in response to either of those rook moves we have sketched, White can play 2. Qxh3, avoiding QxQ and preparing to interpose the queen on f1 if Black plays RxR. But then he still loses the queen—and also both rooks. It goes 2. …RxR+, 3. Qf1, RxQ+, 4. KxR, QxRh1+. Black has a queen left and White has nothing.

Black's best reply to 1. Re4 is probably 1. ...Qe5, which avoids the mate just shown but loses his queen and then his bishop.

Dg369: Another variation on the same idea, this time from Black’s side. Where does Black have the makings of a discovered attack?

Dg370: Black to move

Dg370: Observe the offensive tension on the board. Black would like to use his queen to take White’s rook on f5, but then he would lose his own rook to White’s queen. How to break the jam? By use of the queen-rookqueen alignment on the e1-a5 diagonal—the three-piece kernel of a discovery. White’s queen is ready to be taken if the rook can vacate c3 with sufficient violence. The rook has no way to give check, but study White’s king: it’s trapped on the back rank. If Black could land a rook there he might have a mate threat—except for the protection furnished by White’s rook on b1; if Black could take that rook with his own, he would indeed threaten mate. So the threat by Black of RxR is almost as good as a check, and Black can achieve this with 1. ...Rb3. What next? White is confronted with multiple threats, so he might naturally look for a way to defuse them both—a square where his queen would be safe and would defend against RxR#. One possibility is 2. Qc1. This takes care of those two problems, but not a third one: Black now can play QxR with no worries, because White’s queen no longer is in position to retaliate by taking the rook on c3. (But before playing QxR Black has to exchange rooks on b1; otherwise White meets Black’s QxR with c2xR.) White is left with a queen against Black’s bishop and queen. A better reply idea for White would be 2. a2xRb3. Black then plays QxQ next move, so this time White has lost a queen for a rook; but at least he ends up with two rooks against Black’s queen and bishop.

Dg371: Black to move

Dg371: First note the kernel of a discovered attack spread along the long h1-a8 diagonal. If unmasked, the Black bishop could take White’s queen. Can the rook be vacated from f3 with check? Yes; Black can play Rf1+, and White would have to reply RxR (his queen would then be pinned). Then Black could play BxQ, to which White replies KxB, and Black has won a queen for a bishop and a rook. Don't settle for this, though; think through all of your options. How else could the rook vacate f3, and with what results? He could threaten mate with RxN, looking to play RxR# next move. RxN therefore has about the same effect as a check but picks up a knight along the way. Now what would White do? Stay aware of every piece bearing on the enemy king’s position. Here Black has a second rook he can involve, this one on the open efile. So if White replies to RxN with RxRd3, Black plays his other rook to e1—and it’s mate. White instead needs to create a flight square for his king, and therefore replies to RxN with QxB. It avoids checkmate but loses the queen. The key thing for Black now is not to play the tempting RxQa8, but to instead use RxR+. It wins a rook, and since it's a check it effectively is a free move; White has to spend his reply saving his king, and so can’t move his queen out of harm’s way on the eighth rank. When Black has finished giving checks and doing whatever damage he can in the process, White’s queen still will be on a8 for the taking. Capturing the rook on d1 first with check, then taking Black’s queen later, is an example of using the priority of check—the principle that a check must be addressed before any other threat pending on the board. It is a valuable idea that we will revisit often and study in detail later.

Dg372: By now the queen-and-rook kernel for Black on the long diagonal no doubt is obvious. Look for a target for the queen if unmasked, and see that White’s queen is loose and ready to be taken on c3.

3.2.3. The Rook Discovers Check.

Dg372: Black to move Black just needs a threat to make with his rook on e5. The rook can’t directly threaten anything at the moment, but the key fact about the piece is that it is part of a battery of rooks aimed at White’s back rank. Play through the first rook capture in your mind’s eye: 1. ...RxR+, to which White replies 2. RxR. Now what? The answer is tricky. Are you inclined to play 2. ...RxR+, checking the king? Not so fast: White’s queen protects e1, so White would be able to play 3. QxR, taking the queen out of danger and dissolving the check at the same time. Any other ideas? Consider the surprising 2. ...Re2, which puts pressure on a square next to White’s king (f2) that Black already attacks with his queen. This allows Black to threaten mate with 3. ...Qxf2; White must do something to prevent it. If he plays 3. QxQ, Black doesn't recapture right away with g7xQ; rather, he first plays RxR+, winning a rook and checking White’s king (the priority of check again). After the king moves to h2, then Black still has g7xQ— and only Black’s rook is left on the board. If White instead plays something other than QxQ on the second move of the sequence, Black plays QxQ on his next move. The hard part of this position is seeing the value of Re2 for Black. The key point to remember is the sensitivity of squares next to the king, especially when they already are attacked by a queen. Adding another attacker against such squares, as Black does here with his second rook, can create a crushing threat even if no check or capture is made with the move.

Dg373: Black to move Dg373: We turn to the power of the rook to discover check. The position on the left illustrates the pattern in simple form. Scan the diagonals and you see Black’s queen behind his rook, with White's king at the other end of the line. The stage is set for a discovered check; Black just needs a good target for his rook. Best would be either White’s queen (because it’s more valuable than the rook) or any unprotected White piece (because then it doesn’t matter whether the rook is more valuable). White’s queen can be attacked with Rc4+; after White protects his king (Kh1 is best), Black plays RxQ. It would be different if White could take his queen someplace where it had protection and blocked the check, but there is no such square. If White plays Qe3, for example, Black has QxQ+; this renews the check and thus gives Black time to save his rook on his next move.

Dg374: Black to move Dg374: Here is another way it can go. Black’s rook masks his bishop, which otherwise

would have an open line to White’s king. What should Black do with his rook? The queens are off the board, so Black looks for pieces he might attack. There are two: White’s knight and rook. Which is the better target? The knight, because it is unprotected; if Black plays Rb2+ and then RxR, he just ends up exchanging rooks after NxR. The winning move thus is Ra2+, followed by RxN after White saves his king.

Dg375: White to move

should go. It will have two moves to inflict damage, and unlike the bishop it can reach squares of either color. Naturally White would like to go after Black’s queen, and he can. But another critical feature of the rook’s powers is that it can move both horizontally or vertically, so there still is a decision to make: White can attack Black's queen with Rc5+ or Rd6+. Choose carefully. Your chief worry in executing a discovered check is that the targeted piece—here the queen—will be able to move out of harm’s way in a manner that also blocks the check. So start by considering Rd6+ and ask whether Black’s queen would have any such moves. It would; Qc4 would block the check and also lend the queen protection against QxQ from the pawn on b5. Now try the other move: Rc5+. This time the only way Black’s queen could block the check is by moving to d5 or e6—but on those squares it gets no protection and so is lost to e4xQ or QxQ. Rc5+ thus is the winning move for White.

Dg375: White’s rook masks the path of his bishop toward Black's king, so White’s task is to find a destructive role for the rook. Again the queens are off the board, and again White is picking between attacks against Black’s rook (with Re6+) and a lesser piece (with Rxb6+, attacking the bishop). Both targets are unguarded at the moment, but Black can reply to the check with Kf7, protecting the rook. So Rxb6+ is better; it wins a pawn and a bishop for nothing. Dg377: White to move

Dg376: White to move Dg376: It starts with identification of an idea: the kernel of a discovered attack. Here you find White’s rook blocking a check by his queen. The only question is where the rook

Dg377: White has a tempting attack against Black’s back rank: Black’s king is trapped in the corner, and White’s queen is poised to move to c8. Should it? The crucial thing to recognize here is that the kernel of a discovery lies on the board—for Black. His rook masks his bishop, which will check White’s king as soon as the rook vacates f2. This is the dominant tactical fact of this position, and it makes Qc8+ a disaster for White; for then Black plays Rf8+—not only blocking White’s check, but winning his queen with RxQ as soon as White takes his own king out of check. White had better play Kh1 instead.

Dg378: Black to move

Dg379: White to move

Dg378: Now a reminder that a discovered mate threat can be formidable, too. The alignment of pieces on the d1-h5 diagonal cries out for consideration of a discovered attack; if Black moves his rook from e2, his queen will threaten not only to take White’s rook on d1 but to mate there—almost; White’s queen presently guards the square. The question for Black is the best use he might make of his rook as it unmasks the threat, and the natural answer is to go after the White queen that protects the rook. He experiments with Rb2. If White plays the capture QxR, Black mates as just noted. Nor can White move his queen to any other square where it will prevent mate. The best he can do is Qxd5, taking a pawn and guarding against immediate mate by protecting the d1 square. But then Black takes the queen with his c6 pawn (or with his own queen—it doesn’t matter) and White has nothing left but Rf1. Black is ahead by a queen and has a won game.

He looks at any captures he can make and considers their consequences—what lines they would open and so forth. There is just one: BxB, resulting in RxB. The interesting feature of this exchange is that it not only extinguishes the threat against White’s a1 rook but also leaves that rook and White’s king with nothing between them—and an enemy target on b2. White therefore can devastate Black by castling: 0-0-0. Suddenly Black’s king has been checked by White’s rook, while Black’s rook is about to be taken for free by White’s king. Castling into an attack is not something you have a chance to do very often, but when the opportunity arises it is memorable.

The discovered attack here seemed at first to be foiled by White’s queen, which appeared to guard the targeted piece. Consider in such a case whether the discovered attack might be turned against the very piece that seems to frustrate it. Dg379: This position is not an especially good fit for the current section because it does not involve a discovery in the usual sense, but it goes here as well as anyplace. White has to do something about Black’s threat of BxR.

3.2.4. Manufacturing Discovered Check. Now let's look at a few positions where some element of the discovered check—open lines or appropriate targets—has to be manufactured. The ideas behind the methods used here will be familiar; only the context is any different from what has come before, but seeing how the old ideas look in new settings will make them easier to see in real time.

Dg380: Black to move

Dg381: White to move

Dg380: Find the makings of a discovered attack for Black in the position to the left. His rook blocks his bishop along the g1-a7 diagonal. The bishop is aimed toward White's king but is blocked by the pawn at f2. Black can't capture the pawn and cause an interesting recapture, so try another idea: capturing something the pawn protects and thus forcing it to move on the recapture. Viz.: Black plays QxB, inviting f2xQ. If White plays the recapture, Black's discovered check has been nicely prepared. All that remains is to find a good target the d4 rook can reach in two moves. Rd8+ unmasks check; then after White saves his king, Black has RxQ.

Dg381: First find the kernel of a discovery; you are trying to learn to see them every time, even when they don't appear to lead anyplace. White’s rook masks the path of his bishop toward Black’s bishop—and, behind it, his king. If Black’s bishop could be replaced with his king, White would have the makings of a discovered check. Capturing the bishop would be one way to achieve this, but again White has no way to do it; and yet again, too, there is the alternative of capturing something the bishop protects—the knight on h5. White can take it with QxN+. If Black recaptures BxQ, the bishop is out of the way and White can unmask a check by moving his rook. He looks for damage the rook can inflict with two moves and sees that Black’s queen is within reach. Rd6+ attacks it; RxQ takes it after Black saves his king. White wins a piece.

Take a moment now to appreciate the threats that Black faces in this position and how the sequence just described would bear on them. White has three pieces aimed near Black’s king: his queen, rook, and bishop. Look at White’s checks and you see that he is poised to play Rxc7+. Black would have to play BxR. Now comes the follow-up check QxB+, forcing Black’s king onto a8; and finally White mates with Qb8. Fortunately it’s not White’s turn to move! The beauty of QxB for Black is not only that it wins a piece by threatening a discovered check; it also defuses White’s threat against c7 by adding a guard to the square (Black’s queen) and by taking out one of the attackers against it (White’s bishop).

Well, but wait: how does Black save his king? He can move it (say, to g7); but he also can save it with a threat by playing his bishop from h5 back to g6, where it blocks the check and also throws a counterattack at White’s bishop. Now after White plays RxQ, Black can play BxB. This would mean White traded away a queen and a bishop to win a queen and a knight—but we aren’t quite done yet. After Black’s BxB, White recaptures with NxB and still wins a piece. So the modest-looking knight on e1 is necessary to make the whole sequence work. (If that knight were off the board, the sequence just described still would be worth a pawn, though; after Black plays BxB, White would have Rb5, forking the loose pawns on a5 and c5.)

The lesson of this last note is to take time to consider how your opponent will reply to the checks you make. If it's clear that he will have to move his king, it may not matter too much where it goes (though then again it might!). But if he has interpositions, you need to anticipate what they would make possible for him on offense.

in the last position, the queen can be sacrificed to force the needed result: Qh1+, requiring KxQ.

Dg383: Black to move

Dg382: Black to move Dg382: Black’s rook masks his bishop on the long h1-a8 diagonal. This might be easy to overlook because there is no White target at the other end; but with the bishop aimed into the corner next to White's king, you readily should appreciate the potential for a discovered check here. The question is whether the king can be drawn into the line of fire. One way to so move a king is to check it with another piece. This is especially forceful when the queen simply moves up next to the king, requiring it to capture to survive; thus here Black can play Qg2+, requiring KxQ. Since this involved sacrificing a queen, you're looking for mate as a payoff; so Black wants to move his rook where it can add to the pressure on White’s king (now on g2) that will be created by the unmasked bishop on b7. The rook can go two places to do this, both involving a capture: Rxf2 and Rxg3. The move to f2 is unproductive since White just replies KxR. Rxg3, however, is checkmate: the rook has protection from the other Black bishop on d6, and it cuts off the only squares the king could use to escape the diagonal. Dg383: A similar idea. Black has the familiar kernel of a discovery on the long diagonal leading toward White’s king. First the king needs to be drawn onto the diagonal; here as

Now the rook’s job again is to both unmask a check and add to the pressure on White’s king. This it does with RxN++, putting the king in double check and so requiring it to move. Its only flight square is g1. Now Black goes in for the kill with Rh1#. The bishop protects the rook and also cuts off the king’s flight square to the north—a classic mating pattern we considered in the chapter on discoveries by the bishop.

Dg384: Black to move Dg384: The kernel for Black again is the bishop behind the rook, and again the bishop’s path leads toward the position of White’s king but not yet quite at White’s king. How can the king be drawn onto the bishop’s diagonal? With the same sacrificial idea considered in the previous positions: Qf2+, requiring White to play KxQ. Now what? Again, with the queen sacrificed and White’s king vulnerable, Black thinks in terms of mate; this means using the rook to add to the pressure on the king’s position by

making a check of its own or cutting off some flight squares. Black could try a double check with Rd2, but trace the consequences: the king returns to the back rank with Kf1, and if Black follows him there with Rd1, the rook gets taken by White’s knight. So what else might Black do with his rook? The key here is to be mindful of all the Black pieces bearing on the situation. After his queen is off the board, Black still will have another bishop at g4 cutting off the square above White’s king (f3) and to the side (e2); Black also has a pawn at f4 that cuts off e3 and g3 (well-advanced pawns can serve very valuable purposes in closing off squares; do not overlook them). This means that once White’s king is drawn onto f2 it will have no escape squares to the north, east, or west; the third rank and the e2 square might as well be filled with White pawns. So the really useful thing Black’s rook can do is cut off the king’s escape to the south by occupying the back rank: Rd1+ unmasks check by the bishop and leaves the king nowhere to go. White can interpose his bishop with Be3, but this just delays mate by a move (Black plays BxB#, with his bishop getting cover from the f4 pawn). Here’s another way to have seen the idea. As Black you notice that your queen and bishop both are aimed at f2, adjacent to White’s king. You might naturally consider Rd1+; this requires a reply from White (NxR) to save his king; and in the meantime the bishop has now been unmasked and is ready to support mate with Qf2. But then you see it doesn’t quite work because once White’s knight is on d1 it controls f2. So you play with the move order and see that if you start with Qf2 it works after all. Dg385: Last, consider a case not of a discovered check but of a discovered mate threat. First find the kernel for Black; it’s on the long a1-h8 diagonal, where his rook masks his queen. The queen's line would pass next to White’s king without directly attacking it. Black has no way to force White’s king onto, say, b2, where it would be directly vulnerable to a discovered check. So what to do? Think carefully about where the queen would be

able to go, and with what results, especially where the enemy king is as exposed as it is here. Black’s queen would have some great threatening squares to land on: think of c3 or a1, where it would attack the king and cut off most of its flight squares. And then remember to consider the significance of other Black pieces trained on the king’s sector—including the bishop on g6, which slices off two more of the king’s escape squares. The idea comes into view: if Black’s rook unmasks his queen—playing, presumably, Rxe2 and attacking White’s queen—Black’s queen would not give check, but might threaten to mate.

Dg385: Black to move Now nail down the details, imagining the particular moves and replies that would be possible. After playing Rxe2 Black is ready to take White’s queen. If White plays QxR, then what? Black plays Qc3, which has become safe now that White’s queen has moved over to take the rook—and it’s mate (after White uselessly interposes his queen), since White’s king has no place to go. In reply to Black's initial Rxe2, White’s preference would be to move his queen someplace where it both is safe and prevents mate, but no such square is available; in fact there is nothing at all he can do with his queen to avoid mate. Instead he has to play RxBg6, extinguishing the mate threat—but surrendering his queen next turn (or the turn after that if Black first plays Qa1+).

3.2.5. Two-steppers: Building the Kernel.

Dg387: White to move Dg386: Black to move Dg386: Here Black does not have the kernel of a discovered attack; the point of the position is that when you see a configuration like this—bishop and rook coordinated, with both trained on squares near the king—it pays to experiment with creating the pattern for a discovery by bringing one piece into the path of the other and examining the consequences. Here an obvious way would be Rc2+: the rook moves into the bishop’s path and gives check; White’s king has to move. If it goes anywhere but d1, it leaves the knight loose and Black takes it with his rook on the next move. (Always ask whether an opponent’s forced move would leave anything loose.) If White moves the king to d1 to protect the knight, he completes the pattern for a discovered check by putting it on the same diagonal as Black’s bishop. Now Black would think about what he could do with his rook in two moves. Don’t obsess over the knight. Think broadly about the opportunities created by a discovered check; look for any White piece Black could attack with his rook in two moves. Rc7+ would unmask check by Black’s bishop, and attack—and then win —White’s rook on h7.

Dg387: White is nervous; his king is trapped in the corner with Black’s queen and bishop trained on its general position though not perfectly coordinated. Plus White's rook may be lost if he removes his queen’s protection of it. What to do?

Look for queen moves that continue to protect the rook and also add pressure against Black. One such move is 1. Qd5, since it not only attacks Black’s bishop while still protecting the rook but also creates the three-piece kernel of a discovered check, enlarging the power of both queen and rook. Indeed, this move wins the game: (a) If Black plays 1. …Qc1+, hoping to divert White’s energies by taking the offensive, White executes the discovered check with 2. Rf1+, blocking the check against his own king and preparing to take Black’s queen after Black moves his king out of check. (Actually, after 2. Rf1+ it goes 2. …Kg7, 3. QxB+, and then White plays RxQ. Black’s queen will remain en prise to White’s rook so long as White keeps checking Black’s king with his queen and doing other damage with it in the meantime. The priority of check.) (b) If Black instead plays Qc6 as his initial response, pinning White's queen, he of course loses his own queen to QxQ. Yes, this capture allows Black to play KxR, but then White plays Qd5+ and wins Black’s bishop with a queen fork. White’s queen is the only piece left when the smoke clears.

and the bishop on g2 still has protection. The king’s only legal escape is to h2—and then play proceeds as described a moment ago, with Bf3+ discovering check and then winning White’s queen.

Dg388: Black to move Dg388: Black is closing in on White’s king. A key feature of the position is the kernel of a discovery on the diagonal leading to g1; keep it in mind as you go through your thought experiments. The natural moves to consider first are any checks. Black has two: Rh2, which loses the rook without compensation; and Bg2, which is a lot more interesting because the bishop enjoys protection from the rook on f2, forcing White’s king to move. Where would it go? It would have two options: h2 and g1. Consider them both: (a) If White plays Kh2, notice that the king would have made itself the target of another discovered check—using the kernel Black created when he moved his bishop in front of his rook. Black would be able to unmask a check by moving his bishop from g2, and so can think about targets the bishop might reach in two moves. The natural candidate is White’s queen. Hence Bf3+; and after White moves his king, Black has BxQ. (b) Now suppose that in reply to Bg2 White plays not Kh2 but Kg1. Again the king would have walked onto the target square of a discovered check, this time the one whose kernel was in place from the beginning. It would be tempting now to play Rf5+, unmasking check and then winning White’s queen in exchange for a bishop after White plays KxBg2. But don’t jump to conclusions; there may be a less costly way to achieve the result. It would be preferable to first force White's king to h2 and then use the discovered check described in the previous paragraph. How? With another check: after White plays Kg2, Black replies Rxe2+. The bishop on e3 now gives check

Dg389: Black to move Dg389: The kernel of the discovery for Black no doubt is obvious: the rook on d3 masks the queen on e2, which otherwise would take White’s queen. The question is what threat the rook can make when it moves. Since it has no checks, think about other ways it can put pressure on White’s king—always keeping in mind any other pieces you have that also bear on the king’s position, since pressuring the king usually requires a team effort. Here Black has a bishop aimed at White's king on the long diagonal, blocked just by the pawn on f3. What would it take to create checkmate from here? If the f3 pawn were eliminated and the rook were added to the assault against the king, that would do it. So Black plays Rxf3. This unmasks QxQ, of course; it also leads to mate when the rook next drops down and plays RxN#—a case not only of discovered check but of double check. White has a move to make after Rxf3, but no way to prevent the result. Notice here that when Black unmasks one discovery he also uses the unmasking piece to set up another one; he moves the rook out of the queen’s path and into the bishop’s path, creating a mating threat. The point: when you have multiple pieces aimed in the enemy king’s vicinity, don’t just look for existing discoveries. Think, too, about how various checks, captures, and threats you might make would create new kernels and new potential

discoveries. Indeed, anytime you move your pieces you want to be careful to notice whether you are bringing one into the path of another, for now you appreciate the power conferred on pieces when combined in this way.

Dg390: White to move Dg390: Where does White have the makings of a discovered attack? On the a3-f8 diagonal, where the bishop is masked by the rook—and otherwise would check Black’s king. Naturally White thinks about moving the rook out of the way, not only to do damage elsewhere but perhaps also to create checkmate by starting with a double check. How can the rook both unmask the bishop and give check itself? With Re8++ or with Rxf7++. Let’s consider each of them: (a) Rxf7++ might seem more appealing because the rook is safe there, enjoying protection from the queen on d5. There is an additional point: with Rxf7++ the rook moves into the queen’s diagonal path, creating the kernel of another discovery—a potentially useful pattern. Follow the king’s path in response. It would have to go either to e8 or g8. If Ke8, White would have the new check Qd7#, with the queen and rook protecting each other and cutting off all the king’s flight squares. Now suppose Black plays not Ke8 but Kg8. He would have completed the pattern for a discovered check—the new one that White started to create with Rxf7; the king would be on the same diagonal as White’s queen. So White moves his rook out of the way, unmasking another check, and once more he looks for ways the rook can add another

check of its own. The simple Rf8 is mate, with the rook getting cover from the bishop on a3—another study in the importance of remembering how all of your pieces may bear on a position. Once again, too, we see how a piece can unmask one discovered check while also moving into position to unmask another, as White's rook does here. (b)From the initial diagram we also can consider the double check Re8++. Black is forced to play KxR. White’s attack might now seem to be out of gas—if you overlook the rook on b1. But it can add decisively by sliding over to the open e-file and giving check. Notice that Black’s king has no safe moves; each of its flight squares is under attack. All Black can do is throw his bishop and then his queen into the White rook’s path, but they are useless interpositions; White plays RxB and then RxQ#.

3.2.6. The Windmill. And now one of the most exquisite of all tactical motifs: the windmill. A windmill generally involves a series of discovered checks in which the masked piece and the unmasking piece take turns checking the enemy king; the masking piece, on its “off” turns, captures one enemy piece after another. (This will become clearer in a minute.) Although a windmill can in principle occur with other pieces, the ones you are most likely to see involve a rook discovering check by a bishop; that is why the motif is included in this chapter. These also typically are cases where the kernel of the discovery does not exist at the outset of the sequence. It has to be built, and in the building of it the enemy king is forced into position for a discovered check. This, too, will be easier to grasp once it is seen.

Dg391: Black to move Dg391: Begin with the simple and modest use of the idea to the diagram. Black has the kernel of a discovered check: his rook masks his bishop’s path to White’s king. Black just needs a good target for his rook. White’s rook won’t do; for after Rf2+, White moves his king to g1, protecting the rook as well as evading the check. Black needs a target farther away. The bishop and pawn on the other side of the board protect each other; does it matter? No. Black plays Rxa2+, taking the pawn; White is required to play Kg1 (the king's only flight square); and now Black brings the rook back to g2 with check. Now the key point: White has to move his king back to h1, and suddenly the position has been reset to the beginning with Black ready this time to go after a fresh target—White’s bishop, now left unprotected. Black plays Rb2+, and after White moves his king back to g1, Black plays RxB. A simple instance of a windmill.

path with check via Rxg7+, forcing Black’s king to move to h8. Notice how the position of Black’s king parallels the position of White’s king in the previous example: it is about to be hit by a discovered check, and it has just one flight square. White unmasks a bishop check and at the same time takes Black’s bishop with RxB. Black has to move his king to g8. Then White returns his rook to g7, forcing Black's king back to h8—and resetting the pattern. Again White unmasks the bishop, and this time he takes Black’s knight with RxN+. Black moves his king back to g8, and so forth. White just slides his rook back and forth, alternately putting Black’s king in check and cleaning out Black's holdings on the seventh rank. Since every White move puts Black back in check, he has no time to stop the carnage. After White finally reaches Black’s second bishop with RxBa7, and Black moves his king yet again to g8, White this time does not return to check the king; he instead administers the coup de grace with RxQ.

Dg393: White to move

Dg392: White to move Dg392: Now a more dramatic use of the same logic. Does White have the kernel of a discovered attack? Not yet; but he can form the kernel by moving his rook into his bishop’s

Dg393: Start by noticing the same rough starting pattern here as in the previous position: White has vertical pressure against g7 and a bishop pointed at the same square. He can give check and form the kernel of a discovery by capturing there with a heavy piece. This time White can’t just take the pawn on g7 and start rolling; the pawn is guarded by the knight on f5. But White has a piece he can sacrifice to the cause: his queen. So 1. Qxg7, NxQ and now the pattern here more precisely resembles the previous one. White plays RxN+, accomplishing two things: the move checks the king, forcing it onto its only flight

square—h8; and it sets the pattern for a discovered check by moving White’s rook into his bishop’s path and forcing Black’s king onto the same diagonal. A windmill is in place. If White moves his rook, the king will be in check and move back to g8; then if White brings his rook back to g7, the king will be in check again and will move back to h8. How to exploit this? White first explores the usual destructive options on the seventh rank with RxB+, discovering check. Black plays Kg8; White plays Rg7+; Black plays Kh8, and the pattern is reset. After White has taken both Black pawns on the seventh rank, White will use the two rook moves made possible by his discovered check not to return to g7 but to reach Black’s queen, just as in the previous problem: he plays Rb7+; Black plays the compulsory Kg8; and now White plays RxQ. White nets two pieces and three pawns with the sequence.

now can move his rook to and fro, repeatedly giving check and inflicting terrible losses as he goes. He starts with the customary liquidation of Black’s seventh rank, discovering check with 3. Rxf7. From there the moves went 3. …Kg8; 4. Rg7+, Kh8; 5. RxB+, Kg8; 6. Rg7+, Kh8; 7. Rg5+, Kh7; 8. RxQ, and White won. Usually windmills occur with the king on the back rank and a rook discovering check against it while roaming back and forth on the next rank forward. But they also can run in the other direction, with the rook running amok up and down a file.

Dg395: White to move

Dg394: White to move Dg394: Here is the most famous of all windmills, delivered by Carlos Torre against Emanuel Lasker in 1925. Again a short setup is necessary. White plays 1. Bf6, dramatically sacrificing his queen to 1. …QxQ. The sacrifice is justified by the pattern the move creates: his bishop and rook are trained on the square in front of Black's king, which has a small range of motion. The windmill is ready to turn: 2. Rxg7+, and Black has to play 2. …Kh8; meanwhile White has moved his rook into his bishop’s path, readying a discovered check against Black’s king in its new position. We have seen this before. Since Black’s king has no squares except g8 and h8, White

Dg395: In this position there again is no kernel of a discovery yet in place for White. But Qg7+ is a natural move to consider; it’s close to checkmate, as it moves a protected queen up next to Black’s king. Black’s only legal response is RxQ. Now the stage is set for the creation of a windmill: White has a rook and bishop pointed at the square in front of Black's king, which has little room to move. Thus RxRg7+ leaves Black’s king only one place to go—h8—and also sets up discovered check by masking White’s b2 bishop with his rook. By sliding his rook back and forth between g7 and various Black targets, White can create havoc while Black stays busy fending off checks. It starts with RxBg6+; Black's king is forced to h7. White plays Rg7+, and Black has to move his king back to h8, resetting the pattern. Now what? White plays Rxh6—and it’s checkmate. A familiar lesson repeats: never forget that your first objective, where possible, is not to take material but to mate.

Now note a possible wrinkle. After White’s first exploits the windmill with RxB+, Black has another option besides moving his king back to h7. He can interpose his f8 rook at f6, blocking the check from White’s bishop. The interposing rook is guarded by its queen, but that is not security enough because at this point White attacks f6 twice—with both his bishop and his rook. Thus White replies BxR; Black recaptures QxB; and now Black loses his queen to RxQ. Black has no pieces left, while White still has his rooks and can force mate soon. But it’s worth seeing the general point, which is that when Black interposes rather than playing into White’s hands by moving his king, he may unexpectedly disrupt the flow of the windmill. In another game this sort of interposition might save a game rather than just forestalling doom.

Dg396: White to move Dg396: White does not yet have the makings of a discovery, but he can create the kernel of one by moving his rook into his bishop’s path. Both pieces are aimed at the square in front of Black's king, so the rook's move to g7 gives check and may create a windmill. May, and does. In the previous positions the trapped king had to shuffle between two squares because all others were blocked by the side of the board or by its own pieces. Here Black’s king is hemmed in by White’s knight on d6, which cuts off e8 and f7. So when White moves his rook from g7 and discovers check, Black’s king will have to go to g8; and when White moves his rook back to g7, Black’s king will have to return to f8. The only question is what White should do with his rook to make the most of this pleas-

ant opportunity. He starts with the familiar destruction of the seventh rank: Rxd7+ (Black plays Kg8), Rg7+ (Black plays Kf8). Now what? Rb7+ (Black plays Kg8); and now RxR+, winning a rook and applying another check from a different angle. Black has no escape from it; all his flight squares are attacked. All he can do is interpose Nf8, but then RxN#. We see again the importance of remembering to look not just for material but for mate.

Knight Discoveries. 3.3.1. Diagonal Patterns. The knight is without peer as an unmasker of attacks. The reason is that a piece generally cannot unmask an effective attack if it moves in the same direction as the piece it is unmasking. Hence rooks can unmask attacks by bishops, but not by other rooks; and a queen usually can’t unmask any sort of attack, because it can move in all the same ways as any of the pieces it might uncover. But the knight doesn’t move like any other piece on the board. It jumps rather than slides. Knights therefore are equally able to unmask diagonal attacks by bishops, vertical or horizontal attacks by rooks, and attacks of either sort by the queen. Plus the knight is a piece with a relatively low value, enabling it to be sacrificed readily for other gains. If you don’t know how to use your knight to unmask attacks by other pieces, you don’t know how to use your knight.

Dg397: White to move

Dg397: We begin with the knight's power to uncover diagonal attacks. In the position to the left, the sight of White’s knight in front of his queen (as well as his rook) should cause immediate thoughts of a discovery; Black's queen is loose, so White will be able to play QxQ if he can find a time-consuming move for his knight to make. The classic timeconsuming move—and usually the necessary one when you hope to win the queen—is a check. White has two with the knight: Ne7, which ruins everything as Black plays QxN, and Nh6, which requires Kh8 and thus wins Black’s queen a move later.

Dg399: See how White’s f4 knight masks his queen. See that Black’s queen is loose. See how the knight can give check in one move (Ne6+). All the ingredients of a discovery thus are in place. The check looks harmless because it is so easily defused with BxN or f7xN; but by then it has served its purpose, which was to gain time to allow White to play QxQ+.

Dg400: White to move

Dg398: White to move Dg398: Find the kernel of the discovery. The pattern of knight-masking-bishop triggers thoughts of a discovered attack. If unmasked by the knight on g4, the bishop has an ideal target in Black’s queen. Also ideal is the knight’s target: it can give check with 1. Nf6+. It doesn't matter that Black can address the threat in various ways; he loses his queen in any event. Thus if 1. Nf6+, g7xN, then 2. BxQ; and if 1. Nf6+, QxN, then 2. NxQ+.

Dg399: White to move

Dg400: You want to spot the kernel of a discovery every time it exists. Here White’s knight masks his queen (don’t be distracted by the queen's backward path of attack). Black’s queen is loose, and so makes a perfect target; White’s knight will give check, and then White will play QxQ. But which check should the knight give: Nd5 or Ng8? When there are two checking options, as there often are with a knight, carefully consider them both. Start by asking how Black would reply to Ng8. His only capture would be Ra8xN. Visualize that move and notice that it pins White’s queen to his king (the alignment of White’s king and queen is a conspicuous feature of the position). White then can play QxR, but not QxQ—and now Black has QxRa1+. So Ng8+ doesn’t work. Now consider Nd5+. It leads to RxN or e6xN, either of which is okay with White; he plays QxQ regardless, ending up with a material advantage after starting the position behind by one rook and threatened with the loss of another.

3.3.2. Vertical and Horizontal Patterns.

Dg401: Black to move Dg401: Find the kernel of the discovery for Black. His knight masks his queen, which otherwise is aimed at White’s loose queen. (The knight also masks the rook on e8, which lacks a promising target. When you have a knight in the center, be mindful of how it may mask attacks in all directions.) If Black’s knight could give check, he could play QxQ; but it can’t. Nor can the knight create a mating threat, nor can it capture anything. So consider whether it can make any other good threats. None of White’s other pieces are loose, but the rook on f3 would make a nice target for a knight regardless of whether it’s protected. So play with a move that attacks it: Ng5. White finds both his queen and rook attacked. If he moves one out of harm’s way, the other gets taken. He thus would play QxQ, a luxury permitted by the fact that Black’s unmasking piece didn’t give check. But now Black doesn’t play the recapture h7xQ; he plays NxR+—and then, after White captures on f3, Black has h7xQ, winning the exchange with the sequence. This is another of many examples of taking advantage of the priority of check—the requirement that checks be addressed regardless of what else is happening on the board. Before you play a natural recapture, consider whether you have other damage you can do first with a check, postponing the recapture until a little later. In this case the discovery only turns a profit because Black can take White's rook with check.

Dg402: White to move Dg402: This position introduces a new type of kernel to absorb: the knight in front of a heavy piece (a queen or rook) on the same file. If White's knight can vacate its square with a check, White’s queen will be able to take Black’s queen, which is loose. White thus plays Nxf6+—a fork of Black’s king and queen. Black has to fend off the check with g7xN; and now the game effectively ends with QxQ+. (If Black instead replies to Nxf6+ with Kf8, then it might seem that White would simply play NxQ, but he can do better: Qxe8#. Notice, too, that with Nxf6 the knight seals off h7 as a flight square.)

Dg403: Black to move Dg403: The kernel in slightly different visual form, with Black’s rook masked by the knight at the other end of the e-file. The White rook on e1 is unprotected, making it a suitable target. As usual the knight’s first choice of threat is a check, this time with Ng3+. After h2xN, RxR wins the exchange.

Black also could try replying to 1. Nxd5 with 1. ...QxN, which protects his bishop on c5, but the protection doesn't last long: White plays QxQ, and then (after Black's recapture) still has RxB. All this now leaves Black with the kernel of a discovery against White on the c-file: his knight masks his rook. But the knight does not have a sufficiently threatening move to make, so the whole sequence is safe for White to play. Dg404: White to move Dg404: Find the kernel of a discovery for White. This time it runs horizontally: White’s knight masks his queen’s path along the third rank. The point: your routine scan of the board needs to include attention to any friendly pieces on the same diagonal or rank or file as the knight. Here Black’s queen is loose, and White wins it with QxQ by first evacuating the knight from f3 with a check— i.e., Ng5+.

Dg405: White to move Dg405: The White knight in front of his rook on the c-file should prompt thoughts of a discovery. Does the rook have a good target? It does: the bishop on c5 is loose. All that remains is to move the knight out of the way in a sufficiently threatening or profitable manner. The knight has no checks or other threats to make against Black’s king. But since White is going to take a piece at the end of the sequence, he can afford to sacrifice the knight for any lesser gain of material and still come out ahead. Thus 1. Nxd5, BxN, and now 2. RxB nets a pawn. (One can’t expect to win a whole piece every time.) Or Black replies to 1. Nxd5 with Nf6-e4, letting go of the pawn but protecting the bishop on c5.

Dg406: Black to move Dg406: Find the kernel of a discovery for Black. There are a few of them: Black’s knight on e6 masks the bishop on c8 and the vertical path of the queen on e7; his knight on f6 masks the queen’s diagonal path toward h4. Your first thought is to see if any of those discoveries has a good target at the end of it, and this leads you to the loose White knight on e5. Black will take it for free with his queen if he can find something violent enough for his knight to do as it jumps out of the way. Checks always are attractive for the purpose, but here none are available. So what else can the knight do? Examine its circle of moves, or consider whether White has any other loose pieces; either way you are led to Nc7, attacking the bishop on b5 as well as discovering an attack against White's knight.

knight’s other possible squares and notice Nc6: a move that both attacks Black’s queen and keeps the White knight safe. Black moves his queen, and White has QxN for free on his next move.

Dg407: White to move Dg407: White’s knight masks his queen. The knight is not on the same color square as Black’s king, so it won’t be able to give check; and the queen’s natural target, the rook on e8, has protection. So study the knight’s circle of moves and ask what other offensive blows it might be able to strike. Its most interesting move is 1. NxB, a capture that threatens Black’s queen. Consider each of Black’s possible responses and then White’s replies. If 1. ...RxN, then now the rook on e8 is loose and White plays QxR. If Black instead plays 1. ...RxQ, White has NxQ+. Either way White gains an edge in material.

Dg409: Black to move Dg409: Now a glance at our current topic from a defensive standpoint. Black needs to move his queen to avoid b4xQ, so he considers Qxa3, which seems to win a loose pawn. But before making a venture like this, especially into enemy territory, look for any tactical ideas your opponent may have in place. Where does White have the kernel of a discovery? The sight of his knight masking his rook on the third rank is cause for alarm; if Black plays Qxa3, White can attack Black’s king and queen at the same time with the crushing horizontal discovery Nd5+.

3.3.3. Building Knight Discoveries.

Dg408: White to move Dg408: Where does White have the makings of a discovery? On both the d-file and e-file, where his knights mask his queen and rook respectively. Look for targets for the masked pieces and you see that on the d-file there is a loose Black knight. All White needs is a good threat for his knight to make as it uncloaks the queen. You might first look at checks and find Ne6; but then what? The knight is lost after f7xN, and then if White plays QxN Black has e6xQ—not good! But then look at the

Dg410: Black to move

Dg410: In knight discoveries, as with any other sort, groundwork often must be laid: targets improved or lines cleared with preliminary exchanges. Start with the study on the left. One of the advantages of a fianchettoed bishop (i.e., a bishop positioned like Black's on g7 here) is that if the knight comes to rest naturally on f6 (or, for White, f3), Black has the kernel of a discovered attack against the middle of the board. The pattern works especially well where, as here, the enemy king has been drawn off the back rank onto f2 or h2; for now the knight can give check with one move. All Black needs is a suitable target for the bishop once unmasked. The protected White bishop now on d4 won’t do, so Black plays an exchange to upgrade it: 1. …RxB, 2. QxR and now the board is arranged for Black to take White’s queen with the discovery Ng4+. (If White is alert he will reply to RxB by retreating his queen to c1 rather than by playing the recapture QxR,naturally preferring to forfeit his bishop rather than lose his queen and face the additional trouble that follows afterwards.)

Dg411: Black to move Dg411: Find the kernel of a discovery for Black. His queen is masked by the knight on c6; his bishop, as in the previous case, is masked by the knight on f6. So now think about the targets available for the masked pieces. The knight on c3 is protected by a pawn, making it an unappetizing target for Black’s queen. But the knight on d4 is another matter. It is protected once, but by White’s queen; and it is attacked once already by Black’s knight on c6. This suggests two sorts

of possibilities: play the discovery with Ng4+ (the same idea seen in the previous problem); then after the knight gets taken, play BxN. But of course this move order gains nothing. It’s just a trade of pieces. So consider the other move order: play the exchange NxN first; if White replies QxN, play the discovery Ng4+, winning the queen. Again, a preliminary exchange serves to upgrade the target.

Dg412: Black to move Dg412: Here is an alternative sequence. The kernel is similar: the fianchettoed bishop with a knight in front of it on f6. Again the target is a White knight on d4; again that knight is protected once and attacked once; again Black has to decide whether to execute the discovery now or do a preliminary exchange first. One difference is that White’s king is not available as a target. Another is that in the previous problem White was defending the targeted knight with a very valuable piece (his queen) and Black was attacking it with a piece that was less valuable (his own knight); so it made sense to make the preliminary exchange first, turn the queen into a target, and then play the discovered attack against it. Here the situation is reversed. White guards his knight with another knight, and Black attacks the targeted knight already with his queen. If Black plays the preliminary exchange QxN first, he loses his queen and doesn’t improve the target. So here he skips the preliminary exchange and just plays the discovery Nxe4. If White replies f3xN, Black has BxN and nets a pawn. If White then takes the bishop with his e2 knight, Black recaptures with his queen.

Notice that with the sequence Black has spent his dark-squared bishop, which was doing important defensive work (look at all the vulnerable dark squares near Black’s king; Black no longer has a bishop to patrol them). From Black's standpoint the wisdom of giving up that bishop to gain a pawn is not clear-cut; some strong players might therefore conclude that the sequence just described wasn’t Black’s best move after all—though it was what Bobby Fischer played in Surgies-Fischer (1957).

Dg413: White to move Dg413: This position requires the same type of decision yet again. It is White who has the makings of a discovered attack a couple of different ways; his queen’s path is masked in one direction by his bishop and in another by his knight. The direction of greatest interest is the one with a good target at the end of it, so White focuses on Black’s knight on d5. It's attacked once and defended once. If White were to give check with his own knight—say, with Nxf6—he could then take the d5 knight with his rook. But his own knight would be lost in the process, resulting in a gain of only a pawn. Since the Black knight is guarded by Black’s queen, which would make a perfect target, the better sequence thus starts with a preliminary exchange: 1. RxN—and now if Black plays QxR, White has the discovered attack Nxf6+, taking Black's queen and turning a tidier profit.

Dg414: White to move Dg414: Two patterns here should attract your attention: the masking of White’s bishop by his knight, and the battery of White rooks on the d-file. Since White’s knight can give check on h6 while unmasking the bishop, everything is in place for a discovery—except a suitable target for the bishop to attack. The knight on d7 won’t do; after 1. Nh6+, g7xN; 2. BxN, White hasn't won anything. So upgrade the target by capturing it with another piece—and then doing it a second time if necessary. Hence the usefulness of having the two rooks on the same file: 1. RxN, NxR; 2. RxN, QxR, and now White has created a worthy target for his bishop. Nh6+ wins the queen after Black fends off the check. In practice, of course, Black probably would play Qb6 on his second move rather than walk into the discovery, in which case White will have won two pieces for a rook.

Dg415: White to move Dg415: The potential for a discovered attack is obvious enough: the e4 knight will give check by moving to f6; then White’s queen will take Black’s queen. But now inspect both targets in search of any obstacles to the idea's smooth execution. Black’s queen is guarded

by his knight. You might like to deal with this by capturing the knight, of course, but how? Consider all the White pieces. The rook on d1 is aimed at the bothersome knight; and the knight is next to Black’s king, which also is suggestive. Play with sequences that would allow the rook to help. First move the bishop out of its way violently, with 1. BxN, g7xB. Now move order becomes important: If White starts with 2. RxN+, he takes out the queen's guard but ruins the discovery he is planning: Black plays KxR, and now White's 3. Nxf6 would no longer give check. So White should instead play 2. Nxf6+. Then Black takes the knight with 2. …BxN; and now rather than 3. QxQ, White plays 3. RxN+. The priority of check requires Black to attend to this threat to his king while the threat of QxQ hangs in the background; after KxR (or RxR or BxR), the guardian of Black’s queen is gone and White takes it on the next move. The point: the queen's guard must be taken out late, not early, if the structure of the discovery is to be kept in place. Notice that after White plays QxQ at the end, Black now has a remaining capture: BxNg5. You therefore must be careful to keep track of your gains and losses. White has gained two knights and lost two knights. He also has lost a bishop and a rook, but in return he has won a queen and two pawns—a good trade. Another, simpler way to look at this position is that White just plays the discovery NxN+, but (a) first sets it up with a preliminary capture (BxN) and then (b) interposes a checking move (RxN+) in the middle of it. Since checks require forced replies, it sometimes is possible to sneak them into a sequence like this with no loss of time. But White can't slip in that capture until he gets his own bishop off the d-file; that's why we have (a) here as well as (b).

Dg416: Black to move Dg416: We turn from exchanges that upgrade or loosen a target to exchanges that draw a target into position. We saw earlier that a king’s knight in its natural first position— here, on f6—often can give check while unmasking an attack if the enemy king can be drawn forward onto the second rank. Here is another example. Notice the kernel of a discovery: Black’s f6 knight masks his queen. Examine the queen’s possible target and see that the bishop on g5 is loose; it appears to be pinning Black’s knight to his queen, but its unprotected status makes it possible to turn the tables. Black just needs a target for his knight to attack as it moves out of the queen’s way. As yet it has nothing; but Black looks for any check he can give and finds Bxf2. If White responds with Kxf2, now Black plays the discovery Ng4+ and wins back the bishop with QxB on his next move, netting a pawn and damaging White’s defenses with the sequence. (If White replies initially with Kd2 rather than KxB, White has achieved a similar result more simply.)

3.3.4. Working with Mate Threats. Sometimes you may have the makings of a discovery but lack anything good for the knight to do when it unmasks the other piece; you would like to give check but aren't within range, and the knight has no obvious threats to make against other pieces either. Remember, then, another idea: look at the enemy king; see its vulnerabilities, and any pieces you have bearing down on its position. Sometimes adding the knight to those other pieces

can create a threat of mate or other serious trouble that can anchor a discovered attack as effectively as a check. The point can be put more generally. You already know it is important to look for checks and to create ways to give them. It also is important to watch for—and create—mating threats, as they often serve similar purposes just as well and are easier to devise. Just aiming a piece at a square next to the enemy king may be enough to create a useful mating threat a move later when you aim a second piece at the same square—and aim it at a loose enemy piece at the same time.

Dg417: White to move Dg417: In this first position, White has a classic arrangement for a discovered attack: his knight masks his fianchettoed bishop, which otherwise could take the loose Black bishop on b7. But what threat can White make with his knight that will keep Black busy? The knight seems far from any targets, and certainly can’t give check from where it now sits. The key is to examine Black’s king and notice that White’s queen already is aimed at a square next to it: h7. If White plays Ng5 his knight adds more pressure to h7, and now White is a move from mate with Qxh7. (The simple pattern of a knight on g5 supporting a mate threat by a queen aimed at h7 is familiar and should be absorbed.) So Ng5 is as effective as a check; Black is equally required to pause to fend off the threat. He will do it with QxN, of course. That then leaves White to play BxB. Is the trade of pieces a wash? No, because Black’s rook is stuck on a8, and will be taken by White on his next move.

Dg418: White to move Dg418: White’s knight masks his queen, which otherwise could take the loose rook on a7. The only question is what White’s knight might do while unmasking the attack. It can’t give check, but might it again add to a threat against a square next to Black's king that already is under attack? Yes: White’s queen is aimed at g7, and the knight can add more pressure to the square with Ne6. Now White has Qxg7# if Black tries to save his rook, so Black instead has to fend off the mating threat and let the rook go on the next move, losing the exchange. White's 1. Ne6 is as good as a check.

Dg419: White to move Dg419: The kernel of the discovery is clear: White’s knight masks his queen. Where can the knight go, and what can the queen then attack? The general answer should be clear from the look of the board: the knight can head in the king’s direction, and then so can the queen; with a single move of the knight they both can attack h7. Meanwhile White’s rook already attacks that square. With three pieces ready to bear down on the territory of Black’s king, think in terms not of material but of mate. Consider Nf6; imagine each pos-

sible response by Black, and each check White would have afterwards. You will find that no matter what Black plays—e.g., NxQ, or g7xN, or RxN, or h7-h6, or g7-g6—White is then able to play either Qxh7# (supported by the knight or rook), or Rxh7# (supported by the knight). It's nevertheless important to notice all of those possibilities. The point: you can use a discovered attack not only to win material but to mate. You might have come at the position a bit differently. White is in a hole; he is down two pieces (though ahead two pawns). He needs to make something happen. The obvious focus of his attention is h7, where his rook and queen are aimed. A natural thought is Rxh7+, with the double check Nf6++ or Ng5++ to follow if Black replies KxR. But you don’t play a sacrifice like that unless you are sure it works, and as it turns out the double check doesn't end up achieving enough to save White. So you experiment with different move orders that likewise attack h7 and realize that Nf6 is not only strong but conclusive.

tion from which it could attack the king a move later? If so, that move might be as menacing as a check, given the constraints on the king’s mobility. Here the knight can move toward the king with Nd5—and a move later White then would be able to play Ne7#. Nd5 therefore is as effective as a check; Black must parry the threat or the game is over. But then it pretty much is over in any event because White plays QxQ. This position is a nice study in how even a knight that seems very far from the enemy king may have the power to make a mortal threat against it. It also illustrates the importance of watching the vulnerabilities of the kings at all times, no matter how distant they may seem from the rest of the action.

Dg421: White to move Dg421: "And what checks would I then have?" Learning to ask this question consistently is one of the secrets of great chess. This position offers two illustrations.

Dg420: White to move Dg420: White's c3 knight masks his queen, which otherwise could play QxQ. But for a discovery like this to work, the knight needs to threaten something even more valuable than the queen—viz., the king. Yet how? The knight is on c3, very far from the Black king on g8. Still, examine the king’s position closely. White’s bishop on h6 cuts off the king’s escape squares entirely; if the king were attacked it would have nowhere to go and might be mated. White can’t attack it now, but might he move the knight to a posi-

The idea here is similar to the previous position but with a slight upgrade in complexity. Again White’s knight prevents him from playing QxQ; again the knight is not yet in position to give check; and again Black’s king is hemmed into the corner by the bishop on h6. The question is whether the knight on d4 can take advantage of the king’s vulnerability in a way that requires Black to make a timeconsuming reply. As in the previous position, look for places the knight can move that would place it one move away from giving check, and then consider the consequences of that potential check to see how bad it would be for Black.

Here the knight can start by moving to c6 (with a capture) and then be a move away from Ne7+—while also unmasking the threat of QxQ. Suppose Black replies with QxQ, and now White plays NxNe7+. How serious a threat would that be? Black’s only legal move would be Kh8; White looks for his next check and finds that he can mate by bringing in another piece: he moves his g5 knight to f7. So if White starts with NxNc6, Black can’t afford to play QxQ. Can he afford to instead play QxNc6? That seems to extinguish White's threat against e7. But again White asks what checks he then would have and sees that this time Qg7 would be mate. (Black's queen was doing important defensive work on f6.) So NxNc6 wins either way.

something to protect his king—e.g., with f2xN, or QxNd4 (followed by Black’s recapture RxQ—after first playing Ng3-e2+ to move his knight to safety with check). One way or another White loses his queen. When you experiment with initial knight moves for Black, such as Ng3, the important thing to remember is that for now you don’t care if the knight easily can be taken, because then you have QxQ. The question is just whether White can afford to ignore the knight move you are imagining. You answer this by assuming that he does ignore it and then asking what follow-up move you would have.

Dg423: White to move Dg422: Black to move Dg422: More fun with knights. The kernel of a discovery for Black should be obvious; his knight on f5 masks an attack that his queen otherwise would have against White’s queen, which is loose. The f5 knight is on a light square and White’s king is on a dark one, so the knight can't give check; but it still might be able to create enough trouble for White’s king to produce the same result. Ask what sort of pressure the knight can put on the White king’s position. By moving to g3 the knight at least cuts off the king’s only flight square: h1. Does this matter? Yes, if Black has another piece he can bring to bear on the king to squash it in its cramped position. Black imagines White replying to Ng3 with QxQ and asks what his next check would be; he sees he would then have the game-ending move Ne2#—another mate with the two knights. So after Black's initial move Ng3 White can’t afford to play QxQ after all. He has to do

Dg423: Notice the kernel of a discovery in the White knight’s masking of his queen; see how White’s two knights both are within a move of bearing down on the king’s general position; observe that the king’s position is cramped. The main structural difference lies in the target: if the f4 knight moves, White only has a bishop to attack with his unmasked queen. But the bishop already is attacked once and protected once, so it’s a perfect occasion for a preliminary exchange: 1. RxB, and then if Black recaptures QxR, the pattern is much like the one in the previous frame. 2. Ng6 cuts off the Black king’s only escape square, allowing White to threaten mate with Nd5-e7; so after Ng6 Black can’t play QxQ. He has to protect his king with a move like h7xN, and then White is the one who plays QxQ. In a sequence like this you have to ask whether the attacked Black queen might have some way to both remove itself from danger and defuse the mating threat by perhaps tak-

ing one of the pieces involved in it. That wasn’t a problem in the previous position because the pieces contributing to the mate threat had protection. But here Black could reply to White’s 2. Ng6 with QxNd5, eliminating both the threat of QxQ and the mating threat of Nd5-e7. Yet after noticing such a capture consider (our mantra) the next check you would be able to play. There would be two here for White: Qxh7, which would not work very well, and 2. Ng6-e7, which would work very well indeed—not only because it forks Black’s king and queen (always think about forks when you move your knight), but because after the compulsory 2. …Kh8 White blows open the h-file and mates there with 3. Qxh7, KxQ, 4. Rh1, Qh5, 5. RxQ#. This sequence might look a little long, but notice that White can foresee the whole thing by simply asking what checks he would have after each of Black’s evasive maneuvers: there never are more than two for him to worry about here, and eventually they lead to mate. The trick is to remember all of your potential checking resources—including the rooks on your back rank, which can be moved to the h-file in a hurry. We will look more closely at this idea in the section on classic mating patterns.

threatening move for the knight. From f3 it can’t check Black’s king, but study the king’s position: once more White’s bishop bears down on it, attacking an adjacent square—the characteristically weak f7 (it's "weak" because only Black's king guards it). If White’s knight can’t give check, can it at least attack that square? Yes, with Nxe5, unmasking QxB. Now assess White’s attack on f7 to see how serious it is. White’s next move—it would need to be a check, and there’s only one—is Bxf7+. In principle the king has three flight squares, but two of them (d7 and f7) are attacked, so Black’s only legal move will be Ke7. What is White’s follow up? Notice that now the king is severely boxed in; most of the squares around it are attacked. Again the important thing is to look for the next check— and to remember other pieces you can add to complete the net. Here the knight on c3 moves to d5, and it's mate. What this analysis means is that Black has to respond defensively to 1. Nxe5, probably with d6xN. This allows White QxB and the net gain of a pawn.

Dg425: Black to move Dg424: White to move Dg424: White’s knight on f3 appears to be pinned to his queen by Black’s bishop in familiar fashion. But we have seen that sometimes a pin of a piece against the queen can be turned into a discovered attack by the queen; this is a particular danger where, as here, Black has left the bishop loose in his eagerness to impose the pin. We just need a very

Dg425: A minor variation. White has the familiar pin of a knight—here on f6—to Black's queen. This time the pinning bishop isn’t loose—yet; but we still ask whether the knight, by moving out of the way, might be able to create pressure on the enemy king. Once more a bishop attacks the enemy fpawn. Can Black’s knight add pressure to that square? Yes, with NxN: now two Black pieces are attacking f2. Is it a mate threat? Follow it out, looking for checks and asking

what comes next after each White reply. It works like the previous problem: Black plays Bf2+, White moves the king to e2, and then Nc6-d4 is mate for Black. The point of analyzing the mate threat, of course, is just to determine that if Black starts by playing NxN, White can’t afford to reply BxQ. He has to play d3xN, ending the mate threat but then losing a piece after White takes the bishop with his queen. The initial discovering move removes the bishop’s guard, leaving it loose after all.

3.3.5. More on Mate Threats: Vertical and Horizontal Patterns.

So instead Black fends off the mate threat and loses his queen, which is loose, presently. We might as well sketch Black's actual play in reply to 1. Nxc6, which can get a bit complicated. Black's best move is Bxb2+. You might expect White to reply KxB, but no: that would allow Black to play Qf6+ next move, using the priority of check to remove his queen from danger. Instead White replies to Bxb2 by simply moving his king to b1. Now Black plays BxN to defuse the mate threat, and White has the move he has been waiting for: QxQ. Or instead of BxN, Black could play his queen to a3; there it seems to be out of danger, and it guards both mating squares: a7 and e7. But then White simply goes ahead with Ne7+, which requires Black to capture the knight by playing QxN. Again, White now has QxQ.

Dg426: White to move Dg426: Find the kernel of a discovery for White. His knight masks his queen on the efile; this formation of three pieces on a line should be instinctively visible. White needs to vacate the knight from e5 in a sufficiently threatening manner to allow him to play QxQ a move later, which likely means he needs the knight to threaten Black’s king. The knight can’t give check, but it can move into the king’s vicinity; and the bishop on g3 is aimed that way, too. Indeed, when the e5 knight moves, it will discover an attack by the bishop on both of the king’s flight squares. Nxc6 thus puts tremendous pressure on the king’s position. It is just as effective a distraction as a check would be, because if Black does anything to save his queen White plays Nxa7# on his next turn. (He also threatens mate with NxQ, or any other move of the knight to e7.)

Dg427: White to move Dg427: The pattern we are considering should be no less evident when the three pieces involved are arranged horizontally, as they are here: rook-knight-rook on the fourth rank. Another signal for White to see is that Black’s rook is loose; it would make an easy target if White could get his knight out of the way and give check at the same time. He can’t, for again his knight and the enemy king are on squares of different colors. But it still pays to study the king and its vulnerabilities. Black's king has little room to move. All its flight squares on the fourth rank are sealed off by White’s king and pawns; so is g5. Indeed, the only place it can go is g6. It follows that White would mate if he could safely attack the king’s current position and g6. A knight can do that sort of thing—but from what

square? In theory there are two possibilities: e7 and h4. The latter square is out of reach, but by moving the knight to d5 White threatens Ne7#; the initial move to d5 therefore is as threatening as a check. Black has to fend off the mate threat. If he tries to create a flight square for his king by moving his knight, then of course White has RxR—the point all along.

This position resembles the mating threats we have been considering lately because in either case the unmasking knight doesn't check or capture as it unveils the discovered attack; rather, it moves into position to threaten a crushing blow a move later.

Ah, but wait: we must consider whether Black might somehow move his target to safety and extinguish the mate threat. He can—sort of— with 1. …Rc7, avoiding White's threat of RxR and also guarding the mating square e7. But this still sacrifices the exchange, as White then has 2. NxR, NxN. Dg429: Black to move

Dg428: White to move Dg428: This position doesn't involve a mating threat but it depends on a similar train of thought. See the kernel of a discovery on the third rank: the White rook, White knight, and Black queen in a line should be suggestive. What threat can the knight make as it evacuates e3? Black’s king is out of range—on this move. But look for moves that would allow the knight to give check a move later, and consider whether that check might be of interest—if not as a mating threat, then as part of a double attack. Black’s king and rook are poised to be forked from h6. Ng4 thus threatens Nh6+. Black has the choice of replying to Ng4 by (a) taking the knight with the h5 pawn, losing his queen to RxQ, and then taking White’s rook with the pawn that would then be on g4; or (b) he can save the queen and lose the exchange to the coming knight fork. Either way White takes a decisive advantage.

Dg429: We always are alert for pieces on the same line, and so have no trouble here seeing the kernel of a discovery for Black on the fifth rank. If his knight could make a substantial enough threat, he could play QxQ a move later. Since the knight can’t give check, think about other threats it could make: is there a square it can reach from which it would then be able to give a check with interesting implications? Yes; with Nxe4 Black unmasks QxQ, and also moves the knight into position to take White’s rook with check on the next move. And Nxe4 does more: it puts the knight into the path of Black’s queen, creating the kernel of a second discovery by Black on the e-file; if White retreats his queen, Black thus plays NxRd2+ and then QxRe1 after White moves his king. To prevent all this, White presumably will respond to Nxe4 with QxQ. Black was ready to allow this because his queen has protection from the bishop at g7, but notice the importance of not recapturing right away. Exhaust your checks first: after White plays QxQ, Black picks up White’s rook with NxR+; then, after White’s king moves, there still is time for Black to play BxQ or d6xQ (the priority of check).

3.3.6. Discovered Check with the Knight.

be reached the move after next. 1. Nc5+, Kf8; 2. NxQ wins the queen for the knight.

Now some examples of patterns that arise when the knight discovers check, giving it two moves with which to create havoc.

Dg432: White to move

Dg430: To the diagram probably is the simplest possible example. The kernel of the discovery should be obvious enough, as it consists of White’s only remaining pieces. If the knight moves from f6, the bishop checks Black’s king. This means the knight will have two unfettered moves in a row. So look for enemy pieces on the same color square as the knight; be ready to move it in any direction. The natural target is the queen if it can be reached, and so it can: 1. Ne4, Kg8; 2. NxQ.

Dg432: The cluster on b3 and c4 is the kernel of a discovered check; White will attack Black's king with any move of his knight out of the bishop's path. Since the knight is on a light square, look for enemy pieces also on light squares that might make good targets. You thus find the Black rook on a8, the Black bishop on b7, and the Black knight on g4. The rook is the least attractive of these possibilities because it's guarded. As between Black’s knight and bishop, the knight makes the better target because White can pick up a pawn along the way: 1. Nxe5+, 2. Kh8; and now NxN.

Dg431: White to move

Dg433: Black to move

Dg431: The simple form again, this time running vertically. The kernel of the discovery should be evident on the e-file. White sees that the king is at the other end of it and thus realizes that his knight will have a free move. Black’s queen always is a favored target; here it’s on a light square, as is the knight, so it can

Dg433: Black is threatened with the loss of a rook on his back rank. Meanwhile he has an offensive opening of his own at the other end of the board: his knight masks the bishop on c5; since the bishop would attack White’s king if unmasked, the key question is what damage the f2 knight might do while Black fends off that check. Do you see how this offensive opportunity relates to the threat of

Dg430: White to move

RxRe8 that currently worries Black? The strength of White’s threat depends on the coordination of his rooks on the d-file; that is what prevents Black from being the one to gain with RxR. Things would be different if the connection between White's rooks were disturbed—and as it happens, Black can cut the rooks off from each other and discover check at the same time with 1. …Nd3+, 2. Kh1, RxR. Black wins a rook; the knight severs the line of protection to White's d8 rook— and then the knight is protected against capture by the Black rook that moves onto d8.

knight to safety with Nf6 (rather than guarding it with d7-d5), producing the result shown here; for this leaves the kernel of a discovery in front of Black’s king. White’s knight now can go on the attack with impunity. Black’s queen is within reach via Nc6+; the queen is lost to NxQ a move later, whether it stays where it is or moves to block the check on the e-file.

3.3.7. Discovered Checks with Preliminary Exchanges.

The more obvious 1. …Ne4+ doesn't work. White again replies 2. Kh1, so now Black can play NxR, thinking he has won the exchange after White recaptures; but White doesn't recapture right away. He instead executes that ongoing threat of RxR+. The priority of check means that he holds the initiative while Black replies Bf8 (forced); and now White still has the recapture BxN waiting for him at the near end of the board.

Dg435: Black to move

Dg434: White to move Dg434: This is the conclusion of a famous trap in the Petroff defense. After the opening 1. e2-e4, e7-e5; 2. Nf3, Nf6; 3. Nxe5, Black should not reply with the symmetrical Nxe4. If he does, White plays Qe2—as happened here (look at the Black knight on f6; imagine it instead on e4, as it was a moment ago). The move seemed to attack Black’s knight on e4, but more importantly it put White’s queen onto the same file as White’s knight and Black’s king. The makings of a discovered attack thus were in place, with Black’s own knight on e4 the only impediment. Black blundered away the game by then moving his

Dg435: Where does Black have the kernel of a discovery? On the g-file, where his knight masks his rook; friendly pieces next to each other always require a close look. Next Black looks for a target for the rook and sees White’s rook on g2—with the king right behind it. Nf5, threatening the queen to make time for RxR a move later, makes no sense; the rook is guarded, and anyway White can end the threat with RxR+. But when the enemy king is close to your target the natural thought is to try for a substitution, even if it entails a temporary sacrifice. So Black starts with 1. QxR+, and, after the recapture KxQ, now has the makings of a discovered check. He only needs a target that his knight can reach in two moves, and of course he finds it in the queen on h6.

queen (whether the queen stays where it is or interposes on d3).

Dg436: White to move

Okay, but what if White instead replies to Rxc2 with QxR? Answer this question in standard fashion: examine every check you would be able to give in return. Black's only check here would be Qe1. No moves the White king could make would save it; White would have to interpose his queen, and whether he does it on c1 or d1, Black mates: QxQ#.

Dg436: The same idea in a different visual setting. White's knight on f4 masks his queen, which is aimed at the Black knight on h6. Black's knight is protected and thus is an unsuitable target, but since it's next to Black's king a substitution is possible: RxN+, inviting the recapture KxR. Now White is ready to play Nxd5+, and—after the king moves— NxQ. Notice that 2. Ng6+ also would work for White, since the knight would have protection on g6 from the rook on g1. But then White wins one less pawn.

Dg438: Black to move

Dg437: Black to move Dg437: Black’s knight masks his queen. The queen doesn't yet have a good target, but it's aimed at the pawn in front of Black’s king; so Black might have a discovered check if the position were jiggered slightly. Consider what other pieces on both sides factor into the position. Black’s rook also attacks the c2 pawn. White’s queen is nearby, at d1. An idea comes into view: Black's knight could attack the queen with Nf2, and unmask a discovered check at the same time, if the pawn on c2 were removed; and perhaps the rook can perform the removal with Rxc2. If White responds with KxR, then Nf2 indeed wins the

Dg438: One reason to look habitually for kernels of discoveries is that they can help organize the rest of your tactical thinking. Where are the kernels here? Black’s g6 knight masks his rook on g8, and his knight on c6 masks his bishop on b7. Both masked pieces are aimed in the general direction of White’s king. The more intriguing kernel is the bishop behind the knight on c6, because that knight can go after White’s queen with Nb4. If the bishop were to give check when the knight jumped out of the way, NxQ could follow. But all this would first require substituting White’s king for his bishop on g2. Can it be done? Work backwards: Black would like to take the bishop with another piece, requiring White to recapture with his king. The only Black piece now aimed at the bishop is the rook on g8. Its path is blocked by the Black knight on g6 and the White pawn on g3. Can those obstacles be removed at the same time? Yes, if the knight captures something the pawn protects. So Black plays 1. …Nxh4, inviting White to reply 2. g3xN. Now the position is easy: 2. …RxB+, 3. KxR, Nb4+ (dis ch); and Black

takes White’s queen on the next move—and then forks White’s rooks to boot.

3.3.8. Discovered Mate Threats.

As with many tactical sequences, this one can be foiled early; White simply declines to recapture when Black plays Nxh4, accepting the loss of the pawn rather than heading down the road toward material catastrophe. So against an alert opponent the value of seeing this sequence is not that you then are able to play the entire thing; it's that perceiving the threat of it allows you to make smaller gains because you know your opponent can't afford to retaliate. Dg440: White to move

Dg439: White to move Dg439: Last, a sequence that involves clearing a path to create a discovered check. Start by spotting the kernel of a discovery for White on the g-file: anytime you have a rook with a friendly piece in front of it, take notice. Here the idea is especially appealing because Black’s king is on the same file. Ask what stands between White and a discovered check. Answer: only the g6 pawn. How do you force a pawn to move? By capturing something it protects. The g6 pawn protects the queen, so White plays QxQ; after Black replies g6xQ, the path on the g-file is clear for the discovered check—indeed, the double check— Ne6++. After Black moves his king (the only possible reply to a double check), White has NxR. Black recaptures and White has won the exchange.

Dg440: Now let's see how it can look when a knight discovery involves a threat of mate. In this case the discovery isn't White's best move, but let's find it anyway. White's knight masks his queen: the kernel of a discovery, even if it's a little hard to notice because the queen appears to have no target on f8. But you always want to be aware of the enemy king and its constraints; it's especially important when you have a piece aimed at the back rank. What happens if White moves the knight and then plays Qf8 a move later? It’s mate. So White has a perfect target for the queen after all in the f8 square. He can play Nc6; and after Black fends off the threat of Qf8#, White has NxQ. So what is White's best move? Qe5+; Black has to reply with f7-f6, which then results in Qxf6#.

Dg441: White to move Dg441: White has the nut of a discovery on the long diagonal leading to h8. His queen has

no piece to attack if the knight moves, but since it’s aimed in the general vicinity of the king you consider squares the unmasked queen could attack, not just pieces. Look for any checks the queen would be able to give and you find Qh8—and see that would be mate. Black would no more be free to ignore that threat than he would be to ignore a discovered check. The knight therefore will have an unfettered move to make after it vacates the queen’s path to h8, and can use it to go after Black’s queen: Nd5, and then—after Black takes measures to avoid being mated— NxQ.

Dg442: White to move Dg442: Here's a harder one. Find the kernel of the discovery: White’s knight masks his queen on the seventh rank. If the knight moves, the queen again has no piece it can target—just a pawn, and a protected one at that. But once more you examine the Black king and find that the queen would have a great square to attack: Qg7 nearly would be mate; only the Black knight on e6 would prevent it. Now the important thing when your pieces close in on the king like this is not to think about the two halves of the discovery in isolation. Think instead about how the two parties to it—here the knight and queen—can help each other. If White plays the discovery 1. Ng5, he threatens NxQ. More significantly, though, the knight also attacks another square next to Black’s king, thus creating the new mating threat Qh7#. Against this idea Black’s knight is no help. He is forced to play 1. ...Rxf6, as this erases the immediate mate threat on g7 (by removing the protection White's queen would have there) and also gives the king a flight square (f8) if White plays Qxh7.

At this point it might seem natural for White to complete the sequence by playing 2. NxQ, but that would be a mistake. Black then would have RxR+ (easy to overlook!), leaving White still with a winning advantage but not an immediate win. Your first order of business when you have pieces bearing down on the king is to look for mate. While Black’s move Rxf6 ends the threat of 2. Qxh7#, the move 2. Qxh7+ still takes control of the Black king’s fate and keeps the initiative, comfortably postponing the capture NxQ through the priority of check. Black’s king is forced over to f8. White again has a chance to play NxQ, but once more he waits, preferring instead to bring another piece into the mix with RxR+. Black’s king is forced to e8. Now White plays NxQ, having used checks to keep that capture available for two moves. Black’s knight, his last remaining piece, has no safe place to go, and will be lost next move—leaving White with a queen, rook, and knight and Black with no pieces at all. Mate follows shortly.

3.3.9. Discovered Check Leading to Mate. Again we consider how an idea seen in prior chapters can apply to the knight: sometimes the piece that unmasks a discovered check can, instead of hunting for material, add more to the pressure on the king or otherwise take part in the creation of a mating net.

Dg443: Black to move Dg443: The position to the left shows how it's done in simplest form. See the kernel of the discovery for Black on the e-file; see that the piece to be unmasked, the queen, is aimed at

White’s king. Should the knight go after material, for example by jumping to g4 and then taking the White bishop on f6 on the next move? No, Black should play the knight to f3, delivering checkmate. From f3 the knight adds a second check, which means the king has to move; and the knight seals off d2, the king’s only flight square. Notice that from the outset Black is threatened with BxQ. This is another reason why a simple discovered check like Ng4 would fail; White would just take Black’s queen. The only discovered checks that will work here are double checks, because they require your opponent to move his king.

flight squares should suggest an attack by the knight, since it can hit them both at once— i.e., with Na6#, finishing the game since White’s rook cuts off the whole d-file. This is another sequence where Black’s threat not only is decisive offensively but also does important defensive work by holding the initiative. If it were Black’s turn to play he, too, would have a forced mate: 1. …Qh2+; 2. Kf1, Qh1+; 3. BxQ, RxB#. One way to defend against a threat like that is to launch an offensive sequence of your own, giving your opponent no chance to get in his attack.

Dg445: White to move Dg444: White to move Dg444: The cluster of White’s bishop and knight on e4 and f3 should jump out at you as the possible basis of a discovery (generally speaking, any friendly piece lined up with a knight should get you thinking this way). The bishop has no target yet in place, but since it’s aimed toward the enemy king’s corner, thoughts of a discovered check come to mind. The king would need to be drawn over a square onto the long diagonal. A simple if costly way to do this is by planting the queen on the square where you want the king to go, forcing it to capture there; thus Qb7+ causes KxQ. Experiment with what might come next: Nc5, a double check, forcing the king to move and so keeping all of your pieces safe. What would Black do? The a8 and b7 squares are off limits to his king (imagine a line through that diagonal), and so is a6 (thanks to your knight). So Black would have to play the king to c7 or b8. Now consider White’s next checks in either case. The pattern of those two

Dg445: Our current logic continues. Everything starts by spotting the kernel of the discovery. Here White’s knight on h4 masks his rook. (When the h-file is open and the enemy king has castled on that side, be alert to the relationships between any pieces you have on that line or able to reach it.) A good first question is whether the piece to be unmasked has a promising target—and, if not, whether one can be created. In this case there's nothing for the rook to take at the other end of the h-file, but the king is close by; might it be moved over? A natural way to accomplish this is with a check, and especially by a check from a piece moved onto the h-file that the king will be obliged to capture there. So consider Qh7, which requires Black to play KxQ. It’s an expensive sacrifice, but since the enemy king is in play it might be worthwhile. Now Ng6+ unmasks check by the rook; what would Black do then? There would be only one legal move: Kg8. Look for a final check and you come to Rh8#, with the rook receiving cover from the knight.

Dg446: White to move

Dg447: Black to move

Dg446: The key feature of this position is the kernel of a discovery for White on the e-file leading towards Black’s king. At the moment the bishop on e7 is in the way; it makes a poor target in itself, because it’s guarded and less valuable than the rook that would be able to capture it. But the position would get more interesting (because it would involve discovered check) if the bishop could be captured and replaced by the king—and likewise if the bishop could be drawn away from the e-file. White considers whatever checks he can give and finds that 1. Qf8+ has the desired effect, forcing Black to play BxQ to protect his king. Now the discovery is arranged, but to what end? It had better be good, since a queen sacrifice was needed to get there. Black’s king is in the type of cramped position you should associate with mating possibilities, so think about using both pieces in the discovery to go after it. 2. Ng7++ is the answer, inflicting a double check that requires the king to move to d8. Look for the next check. Here it’s Re8— mate. (Notice that 2. Nc7++ works as well as 2. Ng7++; again Black’s king is forced to d8, and again White mates with Re8. It might seem that if White plays Nxc7 Black could then escape a move later with KxN, but White’s bishop protects the knight from h2.)

Dg447: Black has the kernel of a discovery leading toward White’s king on h3-g2. He could use his knight to go hunting for Black’s queen, but the idea is complicated by the attack underway against his own queen; and in any event, when the king’s position is so cramped it makes sense to focus on the possibility of mate. If Black's knight moves, White’s only option is to move his king to e1 or g1. Imagine the knight out of the way— moved to h4—and consider how it could go after the king on either of those flight squares.

The details differ, but at a higher level of generality our current pattern thus repeats: queen sacrifice; check; checkmate.

(a) If White plays Ke1, what checks does Black then have? QxB, which doesn’t work; and NxN, which is mate because the bishop on e2 is pinned. (b) If White instead plays Kg1, NxN no longer works because BxN results, the bishop not being subject to a pin. But this time the queen check does work: Qg4# ends the game. This is a good study in the value of carefully examining the checks you can give at every turn. After Black's first move the White king has two places to go. Either way, Black has two checks; and either way, one of them is ineffectual while the other is mate.

Dg448: White’s knight on e4 masks the paths of his rook and queen (it's an example of something nice that can happen with a knight in the center); the queen is the more important piece, of course, because it has the king as a target once the knight moves. How to exploit this? If the knight goes to f6, then of course

Black takes it out and avoids the check with KxN. But don't give up.

Dg449: White to move

Dg448: White to move The king’s position doesn't look as constrained here as it did in the previous position, but its mobility still is quite limited because White has several pieces bearing down on it. If there is a mating net to be created, every move in it almost certainly will be a check; so imagine going through with 1. Nf6+, KxN, and then examine any checks White would have and their consequences. The most useful of those follow-up checks would be 2. Nh5+. As you consider Black’s reply you might imagine a dark line leading through the squares on the White queen’s diagonal and another line all the way down the e-file, since those squares all are off limits to the king. And g7 is off limits, too, because it’s attacked by the knight. In fact the king’s only flight square would be f7. Now look for White’s next check, keeping in mind that every square adjacent to Black's king is under attack except g8. Qh7# seals off that square and attacks the king as well, leaving it nowhere to go and ending the game. The position is a good illustration of how a king can be tightly constrained even when it has lots of empty squares nearby—if those squares are under attack. It takes some practice to get the hang of seeing this; it's worth a little time.

Dg449: A horizontal study. White has the kernel of a discovered attack on the seventh rank; his rook is aimed toward Black’s king. Even if the path of the discovery is blocked for now by the bishop on g7, this configuration is a valuable asset and can guide the thought experiments that follow. Consider White's checks and their consequences. Qh6+ is most interesting, as the queen is protected; it forces either BxQ or Kg8. What next? (a) If Black chooses BxQ, it clears the way for the discovered check we had hoped might materialize: now Ng5++ forces the king to h8 (notice that White’s bishop on b3 also participates). And then Rh7 is mate. (b) If Black plays 1. …Kg8 instead of 1. …BxQ, then 2. Qh8+, BxQ; 3. Nh6# likewise is mate via discovery—this time using the bishop on b3, which the knight also was masking. The queen sacrifice on h8 serves to leave that square blocked, further constraining Black's king. The trick to the position is seeing that the knight masks pieces in two directions, both aimed in the enemy king's vicinity. This creates multiple chances for game-ending discovered checks once Black's king is pushed around a bit. More generally it's a valuable study in the importance of thinking beyond the two obvious pieces in a discovery; White finally uses four pieces to wrap this position up. 3.3.10. Building the Kernel: Diagonal Patterns.

The usual position in this chapter starts with the kernel of a discovery in place at the outset. Perhaps the target needed to be created or improved, or maybe a good threat needed to be found or made for the unmasking knight; but the idea was in place from the start and easily triggered trains of thought about how it might be made to work. We now consider some cases where the kernel is not in place at the start—where it first must be built with an initial move that creates the familiar masking pattern while also forcing a reply by your opponent. The forced move itself often adds one of the necessary elements for a discovered attack, usually by moving a target into place. Then follows the unmasking move that attacks two points in the enemy camp at once, requiring one of them to be forfeited. Visually your task is to become alert to moves that put one of your pieces (in these cases a knight) into the path of another, and then to go through the familiar process of imagining how the discovery might be perfected.

fectly safe, as opposed to Nf6+)—and then he has QxQ after Black moves the king from h7. The trick to the position, of course, lies in seeing the kernel of a discovery when it isn’t on the board in front of you but will be created by a move or series of them that you are contemplating. The prospect of a discovered attack would not occur to you in the original position; it only comes to mind once you experiment with Qc8+ and observe what it does. When you think of a move that puts one of your pieces in line with another, pause to consider the tactical side-effects for you—or for your opponent. Notice, by the way, an amusing mating possibility if Black blunders into it: 1. Qc8+, Kh7; 2. Nf8+, Kg8; 3. QxQ, KxN; 4. Qc8#—a back rank mate made possible by Black’s silliness in allowing his king to get trapped behind his pawns and rook with no defender.

Dg451: White to move Dg450: White to move Dg450: In the position on the diagram, assume Black just made a capture with his knight on b5; now the natural tendency for White would be to play QxN. Don’t do it. Always examine your checks to see where, if anyplace, they lead. Here White has the interesting Qc8+. You see that this forces Black’s king to h7, and that White then runs out of good ways to hunt the king down. The crucial thing is not to give up then, and instead to back up and see what patterns would be in place. White would have formed the kernel of a discovery: his knight now masks his queen’s path toward Black’s queen on g4. White can unmask the attack with check—Nf8+ (per-

Dg451: White has no good discoveries to unveil at the moment; his bishop on g2 is behind his knight, but the bishop lacks a good target. So White experiments with other moves and finds that two—Nc5 and Nd6—are of special interest: they both move the knight into the path of White’s other bishop on a3, creating the kernel of a discovery. Examine such moves carefully to see whether they might also force an enemy piece into place as a target of one of the pieces in the kernel. Nc5 is unattractive because it doesn’t force anything (it’s also bad because it lets Black uncramp his position by exchanging knights). But Nd6 is another matter; it attacks Black’s rook. Taking the knight with QxN is out for Black

because the knight has protection; the rook must be moved instead. But where? It has three possible squares: g8 (leading to the smothered mate Nf7#), f8, and e7. The key point about either of the last two possibilities is that they move the rook onto the same diagonal as White’s bishop on a3, creating a target for it once it is unmasked. The knight then on d6 just needs a violent move to make as it unmasks the bishop. Giving check on f7 wouldn’t work because it enables the rook to both extinguish the threat and take itself out of trouble. The correct move is NxBc8. If Black recaptures, BxR wins the exchange for White on the next move; if Black doesn’t recapture and spends his move saving the rook, White has won a piece. As this case shows, moves that create the kernel of a discovery are most interesting when they make a side threat against the enemy at the same time; for then he has to spend a move dealing with the threat rather than dealing with the discovered attack you've just constructed.

Dg452: Black to move Dg452: Find the discovery for Black. The most promising kernel is on the long diagonal where his knight masks his queen, but it's no good because the rook on d4 is protected. So Black plays with other moves; he looks for any checks he might give and finds Nf3, forking White’s king and rook. If White defends with g2xNf3, he opens a line to his king on the g-file—an interesting result. Consider whether the move gives Black any new checks and you find Qg6+. It forces White's king onto h1—and (the key point to see) slides Black's queen onto line with its knight

and White’s queen, creating a new kernel of a discovery. With the king moved to h1, the knight on e4 can give check, and unmask a discovery, with Ng3. After White takes Black’s knight, as he must, Black plays QxQ. White doesn’t have to defend against the initial knight check with 2. g2xN, of course. He can play 2. Kh1. Then Black wins the exchange and a pawn with 2. …NxR; 3. e3xNd4, Qxd4.

Dg453: White to move Dg453: It's important to be alert to mate threats. One way to find them is by looking at any pieces already attacking squares adjacent to the king. Here White’s knight attacks g7, and the square is protected only by Black’s king. If White were to add an attack on that square by his queen, he would threaten mate, so naturally he looks at Qg4. The move not only creates a mate threat but also moves the queen behind the knight on f5, creating the kernel of a discovery—the two queens with a knight between them. How would Black respond to the mate threat? He can play g7-g6; but even so, Nh6, while not threatening mate, then gives check and unmasks the capture QxQ. Again we see that the key is to create the kernel while also creating a side threat that busies your opponent.

Dg454: White to move

Dg455: White to move

Dg454: No doubt you see the kernel of a discovery: White’s knight masks his bishop on the h1-a8 diagonal. But not much can be done with it; the more fruitful thing to notice is that White has a bishop bearing down on the king on the other long diagonal—and that White can create the kernel of another discovery, and also give check, by moving his knight to f6. That move both masks the bishop with the knight and forces Black’s king over to h8, putting a target into place for a discovered check. Now the knight will have two unfettered moves, so it heads toward Black’s queen via his rook: NxR, followed next move (after Black avoids the check from White’s bishop) by NxQ.

Dg455: When pieces are collected on a line, as they are on the b-file here, it is natural to wonder how you might take advantage of the arrangement. Or you might simply consider every check White can make and see Rb6+. Either way the point to see is that Rb6+ creates the kernel of a discovery, with White’s knight suddenly all that stands between his rook and Black’s queen. Usually—and here— a move that so creates the kernel of a discovery is really interesting only if it also helps create the other elements of a discovered attack by forcing targets into place. In this case Rb6 also forces the king to find a new square, and its choices are limited to a8 and c8. Whichever move Black makes, the king ends up on the same color square as White’s knight and is checked on the next move with Nc7+ or Na7+. After the king avoids the check, White takes Black’s queen.

The only fly in the ointment is that after White plays Nf6+ at the outset, Black can end the threat with NxN. How to remedy this? With a preliminary exchange: 1. QxN, BxQ, and now play continues as described above with Black’s defender of f6 eliminated. The queen sacrifice is costly, of course, but it pays off soon enough.

Notice the style of thought: take note of moves that put one of your pieces onto a line with another that can unmask it; consider whether any of those moves also force a reply from the other side, and especially whether they force a target into place.

3.3.11.Building the Kernel: Vertical and Horizontal Patterns.

Dg456: White to move

Dg456: White has lots of ways to give check with his queen, so inquire into the consequences of each. The most interesting is Qe6. Why? Because it moves the queen behind White’s knight and Black’s queen on the efile; it thus puts three pieces on a line in the familiar formation for a discovered attack. Again, moves that so create the kernel of a discovery usually need to force other changes on the board that keep the enemy busy and that may also create the remaining elements of the tactic. Here Qe6+ not only creates the kernel of a discovery but also gives check, forcing the king onto either h5 or h7. Either way, with Nf6+ White’s knight will give check and unmask QxQ.

Dg457: Black to move Dg457: Black’s knight masks his bishop, but the bishop lacks a good target if the knight gets out of the way. So think about other things to do with the knight. See how it can jump into the path of the rook on the e-file, creating the kernel of a discovery. It appears that the rook would have no target, but remember to ask whether the knight’s move might force useful adjustments by the enemy. What threat would Ne3 make? It would fork White’s rook and bishop. White would want to move the rook out of the way, but if he removes it from the first rank he leaves the bishop loose. To protect both pieces he therefore has to play Re1—and this puts his rook in line to be taken by the the discovered attack Nc4+. Black wins the exchange.

Pawn Discoveries.

3.4.1. Introduction; Simple Cases. Pawns can only move forward, so the patterns they create when discovering attacks take two forms. First, they can unmask diagonal attacks by bishops and queens, and horizontal attacks by rooks and queens, as they move up the board; this makes it important to notice anytime a pawn is on the same diagonal as a friendly bishop or queen. Second, and interestingly, by making a capture and thus moving diagonally a pawn can unmask a vertical attack along a file by a rook or queen. This means you want to notice anytime you have a pawn in front of a rook or queen on the same file—not an uncommon state of affairs—and to think about whether the pawn can make a capture (or whether a capturing opportunity can be created) so that it unleashes a discovered attack. We won’t be distinguishing very carefully in this chapter between ordinary discovered attacks and discovered checks, because discovered checks comprise such a large part of the universe of all pawn discoveries. It's very useful to have a check at one of the two ends of a discovered attack; and since pawns rarely are in a position to check the enemy king themselves, the job of giving check very often becomes a task for the other, unmasked piece.

Dg458: Black to move Dg457: Begin with the example to the left, where it's Black's turn to play. Perhaps the most common form of pawn discovery is this pattern: a discovered check that arises when

you have a bishop or queen aimed through the middle of the board at the enemy king, and with one of your pawns blocking the way. If the pawn can move forward with a threat, the results can be crushing. Here Black has d4-d3, forcing White either to move his king and lose his queen to d3xQ, or (the better move) to sacrifice the queen by moving it to f2, allowing it to be taken there, and then recapturing with the rook.

Dg459: The pawn discovery in horizontal form. Here the eye-catching pattern again is the alignment of the two queens, this time on the same rank. If White’s pawn on e5 moves forward, the queens are exposed to each other; but of course for this to work the pawn needs a big threat of its own. Hence e5-e6+, and then QxQ next move.

Dg460: White to move Dg458: Black to move Dg458: Here is a true discovered attack (not a discovered check) by a pawn. The most likely tip-off to the idea is the presence of the two queens on the same line—here, a diagonal. (It pays to be sensitive to alignments of all sorts.) If the pawn between them can vacate the diagonal and give check at the same time, Black can play QxQ a move later. So f4-f3+ wins. It's very simple. You might also have noticed this, of course, by just considering every possible check and its consequences—the lines it opens, etc. It takes some time to internalize the idea that a pawn on the same diagonal as a bishop or queen is such a powerful tactical weapon.

Dg459: White to move

Dg460: A pawn usually will not be in a position to give check, but it may not need to be in order to make a significant threat. The power of a pawn lies in its expendability. Here White has the kernel of a discovery on d4 and e3, where his bishop is masked by a pawn. The bishop has a loose knight as a potential target; after 1. d4-d5, Black retreats his queen to e7 and White then wins a piece with BxN. Since the target of the attack—the knight— can’t strike back at the bishop attacking it, the threat the pawn makes need not be enormous. Almost any threat against a piece would do, in other words; it wouldn’t need to be against the queen or a loose piece. The key to this idea in this position just is noticing it. This can be done by experimenting routinely with possible pawn advances, or by habitually looking at a piece like the bishop on e3 and following its potential path through any pieces in its way that might be moved, or by focusing on loose enemy pieces like the knight on b6.

By the way, notice that Black almost can win the exchange here. Suppose he replies to d2d4 with Qg6. Then after White plays d4xB, Black still has the pawn on g2 pinned. He plays Bh3, threatening to mate with Qxg2. To stop this, White can play g2-g3—but then Black wins the exchange with BxR. What prevents this is White’s queen on d1, which he can move to f3 instead of playing g2-g3. It's a pattern worth knowing. Dg461: White to move Dg461: Familiar idea, different direction. A fianchettoed bishop on b2 or g2 (or the equivalent squares on Black's side of the board) often is easy to mask and unmask with an advancing pawn; here, with a pawn on c3 in front of White’s b2 bishop, White has tremendous potential energy on the long diagonal, and Black plays there at his peril. In this simple position both parties to the discovery have open lines to good targets: c3-c4 unmasks BxQ and attacks—and wins—Black’s bishop on d5.

3.4.2. A Step Up in Complexity.

Dg463: White to move

Dg462: White to move Dg462: A pawn can unmask an attack even when starting from its original position. Notice that at the start of a game each side already has the kernel of a pawn discovery in place: the pawns on d2/d7 and e2/e7 mask the bishops behind them (the queen is poised to be unveiled, too, but set it aside for now). If Black puts a piece near the middle of the board and then leaves another on one of the bishop’s diagonals, he may be asking for trouble. Here White can unmask an attack on Black’s queen by his bishop with d2-d4, also attacking and winning Black’s bishop after the queen moves.

Dg463: The forward progress of White’s rook on d1 appears to be blocked by the pawn on d4; a better way to think of the position, however, is that the rook merely is masked. The difference might not matter if the pawn had nowhere to go but straight ahead, but in this case it can make a capture—and in the process it will change files, thus unmasking whatever attack may lie behind it. Thus d4xc5 attacks Black’s queen and also discovers an attack on Black’s rook, which previously had been attacked once and defended twice. You still don't have enough power to take the piece down, but you could change that by first using your rook to get rid of the knight on f6. All this is the beginning of the idea, not the end of it. Since neither move you are planning would give check, you have to ask whether Black might reply with a check of his own. He could: Black plays 1. ...RxR+ and the threat is over. So now consider starting with a substitution: QxR+; the thought would be that if Black replies with KxQ, his king ends up

on the d-file and d4xc5 becomes a discovered check. But this time there is another problem. Black need not respond to 1. QxR with KxQ; he can play NxQ instead. These obstacles, too, are no reason to give up. They simply focus your inquiry and lengthen the sequence you are planning. You see that the knight on f6 obstructs your idea, which you knew anyway; so you take it out first: 1. RxN, g7xR. Then comes 2. QxR, KxQ, setting up a check for your next move: d4xc5+, and White wins a piece (he gave up a queen and a rook to win a queen, a rook, and a knight).

Dg464: Black to move Dg464: Sometimes the chance to play a pawn discovery can pop up in the middle of a forced sequence. Black has little to work with here, but he can give a safe check with Qh5, so he considers White’s response and sees that it is tightly forced: Kg1. The other interesting thing about Qh5 is that if you examine the queen’s new lines you see that it is aimed at the rook—the loose rook—on d1, with only a Black pawn between them. Once White moves his king the pawn can step forward to f2 with check; White escapes with Kxf2, but then Black has QxR. You might also have seen this by starting with the loose rook on d1 and examining whether your queen somehow can attack the rook and White’s king at the same time. Qh5+ almost does it, at least aiming the queen at both pieces. You observe that your own pawn is in the way; you see that it can’t be removed in advance; and then you play with the move order and see that the pawn that seems to block the fork actually is the key to creating a discovered attack.

Dg465: White to move Dg465: White has a check that requies inspection in Qh4. Notice its attractive properties: it plants the queen flush against Black’s king, but with protection; and (the new point) it aims White’s queen at Black’s queen, but with a White pawn between them—the kernel of a discovery. Black’s reply, Kf5, is forced. Now White plays the discovered attack g3g4+. Black moves his king again. White plays QxQ next move. It's common enough for checking moves like Qh4 to create potential discovered attacks even if that possibility had nothing to do with your initial interest in the move. The important thing is to see the kernel of a discovery every time it is formed, even inadvertently. So when you imagine moving a piece for the sake of giving a check or for any reason, pay careful attention to the new lines it occupies and any possible discoveries you may be creating (or walking into) there. The practical cues are any pieces already on the lines running from the square you are planning to occupy.

Dg466: Black to move

Dg466: It’s clear how Black should begin thinking: with checks like Qf1 or Qe1. Either move forces White to play Kb2 or (if Black starts with Qf1) Kd2. But then what should Black do? You will see nothing more if you confine your attention to follow-ups with your queen. The key to the position is to notice the kernel of a discovery that exists from the beginning (and which is kept intact by Black's Qf1)—the two queens with a Black pawn between them. Or you might see the solution by simply asking what check Black can give after White has moved his king and remembering to include pawn moves in your thinking. The point either way is that if Black starts with 1. …Qf1, he can follow it with the pawn discovery c4-c3+, permitting him to play QxQ next move.

Dg467: White to move

3.4.3. Arranging Pawn Discoveries on Diagonals.

Dg467: What are the critical visual facts of the position to the left? They are, first, that White’s pawn masks his bishop (the formation on b2 and c3 should strike you right away); and, second, that White’s bishop and queen both are aimed at the square in front of Black’s king. Since White’s pawn can attack Black’s queen with c3-c4, the important question becomes the target at the other end—on g7. If White plays c3-c4 now, he also threatens mate with QxN. Sometimes a mate threat is as good as a check, but not always, and not here; the chief difference between them is that a mate threat gives the enemy a wider choice of replies. If he can inflict a check of his own—especially with his threatened piece— he may be able to put out the fire without doing anything about his king. That is the trouble in this case: after c3-c4, Black has the check Qd1. Now White is the one whose move is forced. He must play his king to the second rank. And then comes the next check: Qd2+, a double attack on White’s king and his loose bishop. White can avoid the loss of the bishop with Qf2, but this wasn’t exactly what he had in mind at the outset.

Now let's consider pawn discoveries that require preliminary exchanges. Our focus will be on a single motif: creating a discovered attack in which the pawn unmasks a diagonal attack by a bishop or queen in the direction of the enemy king. Afterwards we will look at a few pawn discoveries that follow other patterns.

Meanwhile, of course, there is a better alternative to all this. Instead of playing c3-c4 first, White starts with the preliminary exchange 1. QxN, KxQ. Now c3-c4+ is a discovered check, giving Black no chance to take the offensive and winning back the queen for White (with the gain of a piece) a move later.

1. …Qe1, by the way, not only doesn’t work but results in mate for White. Notice that White is close to mating already with his rook and queen; he does so as soon as Black runs out of checks that hold the initiative. Thus 1. ...Qe1; 2. Kb2, c4-c3+; 3. Kb3, and Black has no way to stop White from playing Ra7+. If Black replies by moving his king to d8, White mates with Qd7 or Qb8; if Black instead moves his king to c8, White mates with Qe8. Studying the operation of White’s queen and rook in this position is highly worthwhile, as their ability to mate by trapping the king in this way (sealing off two ranks) comes in handy. What also makes it work, of course, is the Black king’s inability to escape toward the center with Kd6.

sic fashion. The obvious hitch is that the path isn’t clear; Black’s e6 pawn is in the way. So go to work to eliminate the obstacle. We customarily remove bothersome pawns by capturing whatever they protect. Here the e6 pawn protects the knight on d5, so Black captures it with RxN, inviting e6xR. Now the discovered check e5-e6 is easy, winning the queen with e6xQ or (if the queen moves to f6) NxQ. Dg468: White to move Dg468: White's rook on h3 is threatened with capture by Black's g-pawn. But White has the makings of a threat of his own: his pawn on e5 masks his bishop. White’s bishop is aimed toward the Black king's territory, the king’s pawn cover is blown, and the e5 pawn can attack Black's queen with a step forward. That move—e5-e6—threatens mate (Rh8), but again the drawback of a mate threat is that your opponent has a wider choice of replies than he does when you give check. Here he would look for a move that defuses the threat and moves the queen out of danger—and would find it with the simple Qxe6, devouring the pawn and giving his king a flight square on f7. No, the better course is to first draw the king into position to be checked by playing Rh8+. Black must play KxR or Kg7; in either case the king is moved onto the long diagonal. Now comes e5-e6+. Black plays Qg7, offering to exchange his queen for White’s bishop to avoid mate. You accept the offer.

Dg469: White to move Dg469: Observe White's queen behind the e5 pawn; the formation invites a search for a discovered check. Think of the pawn moving forward and attacking Black’s queen in clas-

Dg470: Black to move Dg470: Black’s bishop and d4 pawn are on the same diagonal, signaling a potential discovery. (Notice the recurring visual pattern: a pawn in the center and a bishop aimed through it and toward the enemy king.) The pawn can step out of the way and attack White’s queen at the same time. The problem is becoming familiar in structure: the pawn on f2 would block the bishop, preventing it from giving check. So remove the pawn by taking something it protects—the g3 pawn, which Black can capture with his rook. But there is a flaw: consider whether the recapture you want would be compulsory or could be made by a different piece; be aware of how many times any piece you might take is protected. Here Rxg3 is met by White not with f2xR but with NxR. So what to do? Just push the plan back a step and start by taking out the knight. Thus Black plays BxN; and now if White recaptures with BxB, Black is free to play Rxg3+. White then would have to reply f2xg3 (if he instead tries Kh2, White looks for his next check and finds Qxh4#). The board is set up for the discovered check d4-d3+, winning the queen.

The probable result of all this is that Black simply takes White’s knight for free at the outset; this is an example of the power of working backwards from an idea, examining the obstacles to its success and considering how each might be removed. The threat can lead to gains elsewhere on the board, since the discovery hanging in the background leaves other enemy pieces more vulnerable than they seem. Dg472: White to move

Dg471: White to move Dg471: It's good practice to pay attention to lines leading toward the enemy king, and to see in a case like this that White has a bishop bearing down on the diagonal where Black’s king sits—and that the bishop is masked by the pawn on d5. If the pawn could advance to d6, the unmasked bishop would give check and the pawn would take Black’s queen a move later. The challenge is to get rid of the bishop on d6 that blocks the pawn’s progress. How? By capturing something it guards, naturally. One thing it protects is the rook on e7. White can take it with QxR. After Black recaptures BxQ, White is free to move his pawn to d6 and win back his queen after Black moves his king. White nets a rook.

Dg472: White’s queen is aimed at Black’s king and masked only by his pawn on e6. If the pawn could move forward with a threat, White would have an effective discovered check. The e6 pawn can’t move forward because Black’s bishop is in the way; and if the pawn were able to move forward it would have no target (promoting on e8 isn't going to work because Black will have the square guarded). If those two problems are perceived clearly it also becomes clear that they can be solved at once if the bishop can be moved to d8. Try putting a piece there to force a capture on that square: Rd8+. Notice that with White’s e6 pawn attacking the f7 square, Black’s king is trapped on the back rank. Black has to play BxR, and now the way is clear for e6-e7+, with the pawn promoting via e7xB on the next move. The idea here might as well have emerged by just looking at checks. White’s only one is Rd8, and Black’s only defense is BxR. If you imagine the resulting position clearly, the discovered check for White is obvious.

Dg473: Black to move

Dg473: Black’s pieces are compressed, and it might appear that his bishop on e7 mostly is helping to protect the pawn on d6 and knight on f6. But it is doing more: it aims through the pawn at the White bishop on a3, which is loose. After the d6 pawn marches forward to attack White’s knight on e4, Black can play BxB. But the board isn't ready for this yet; White would be able to ignore the pawn and play BxB himself. After Black plays the recapture NxB, White can move his e4 knight away with no net loss. Black’s problem is that his pawn needs a better target—one that requires immediate attention and thus creates time for him to be the one to play BxB a move later. The natural way to achieve this is to capture the pawn’s current target with a different piece and invite a recapture. Thus Black starts with NxN. White has to either forfeit the knight or recapture with his queen; and if he does recapture QxN, the pawn advance d6-d5 now has a very different significance: White is forced to move his queen (and he can’t move it anyplace where it can protect the bishop) and then suffer the loss of a piece with BxB.

square where you want it by putting one of your own pieces there. Thus suppose Black plays Rf2. What does this threaten? Consider the best checks Black would then have; he could play Qg2# or Qxh2#. After Black starts with Rf2, White can fend off that threat of Qg2# by playing Rg1; now g2 is defended. But that doesn't help with the threat of Qxh2#. The only way for White to deal with that threat as well as the threat of Qg2# is by responding to Rf2 with QxRf2. That does take care of both mating threats—but now Black's discovered check e4-e3 wins the queen for a rook.

Dg475: White to move

Dg474: Black to move Dg474: Black’s bishop is aimed at White’s king with the usual pawn in the way. If White’s queen were on d2 or f2 rather than e3, Black would have a classic discovered check with a threat against White’s queen. Meanwhile Black also has two other pieces— his rook and queen—trained on the White king's territory. How to exploit all this? Use one threat to improve the other. More specificially, try the same logic seen in the previous frame, in which you draw the queen onto the

Dg475: White's bishop on b3 is masked by a friendly pawn. It lacks a suitable target but is aimed toward the Black king's general vicinity. The c4 pawn, which would do the unmasking, can attack Black’s bishop on d6— not bad, but an upgrade of the target would be nice. White goes to work at both ends of the possible discovery. First comes 1. RxB, QxR (improving the target White anticipates for his pawn); then 2. Bxg7, which forces Kg8 (improving the target for the bishop once uncloaked). Notice that if White had started with Bxg7 it would have been foiled by QxB; by playing RxB first, White forces Black’s queen to leave its defense of g7. So now both pieces in the discovery have good targets: c4c5+ attacks Black’s queen with a pawn and attacks his king with a bishop. Black has to lose his queen for a bishop by moving it to d5. Of course Black also can avoid much of this by accepting the loss of his bishop on the first move without a recapture—a satisfactory result for White.

Dg476: Black to move Dg476: This time Black’s b7 pawn masks the horizontal path of his queen. This idea would most easily be triggered by the sight of White’s bishop loose on a7; when the enemy has a loose piece, you think hard about whether any of your pieces can find a way to attack it—including any pieces aimed at it whose paths might be cleared somehow. Black almost is ready to go with b7-b5, attacking White’s rook and unveiling the threat of QxB. But consider White’s replies and whether he would be able to go on the offensive himself, especially since Black’s move wouldn’t give check. White would indeed be able to play RxR+. Black then would have to play QxR, ending the threat to White’s bishop with no gain. So again a preliminary exchange is in order to upgrade the target: Black starts with RxR, and after White recaptures with QxR the calculus runs differently. White has no good answer to b7-b5. He has to move his queen and endure QxB by Black next move. (White would like to move his queen someplace where it safely can defend the bishop, but it has no such square.)

Dg477: White is considering Ne5. A good idea? No; for it is important to notice any discovery kernels your opponent has, not just your own. Here Black’s bishop on b7 is masked by his pawn on c6, and this represents a major threat to White on the long diagonal. While White’s king isn't on that diagonal at the moment, he has to be wary of any moves that would expose him to sequences following the general pattern seen several times above. If White's knight moves, it clears a piece from that diagonal and the only thing then standing between Black and a discovered check is the need to draw the king onto g2—accomplished easily enough by capturing the pawn on that square and forcing a recapture with Qxg2+. After KxQ, Black plays c6-c5, winning back the queen and netting a pawn. It might have occurred to you to worry as well that after White’s Ne5, Black would play the discovered mate threat c6-c5—threatening Qxg2# without needing to move White’s king into position. But this is another of those cases where a mate threat is not as effective as a check because it leaves White time to take the initiative with a check of his own: Qxd7+, with protection from the knight (which by then is on e5). After Black’s king moves, White has NxQ. So Black is better off replying with 1. ...Qxg2 as described above—and you are better off assuming your opponent will play the smart response to whatever you do. This batch of studies nicely illustrates the power of a fianchettoed bishop—in other words, a bishop moved from its original square to b2 or g2 (for White) or b7 or g7 (for Black).

3.4.4. Arranging Pawn Discoveries on Ranks and Files. Now consider what can happen when a pawn unmasks an attack by another piece by clearing its file or rank.

Dg477: White to move

Dg478: White to move

Dg479: White to move

Dg478: The kernel of a pawn discovery takes practice to see because it can look so unassuming. A pawn on the same rank or file as a rook or queen, or on the same diagonal as a bishop or queen: these are the patterns to absorb, and they usually look innocuous to the untrained eye. The position to the left is a good example. White’s queen is masked by his pawn on f5 and an enemy pawn on f7. True, White’s rook on d1 also is masked in a somewhat similar way, but the queen is more interesting because it's aimed at Black’s king. A sequence that would clear the pawns from the f-file might create a discovered check or mate threat.

Dg479: White’s rook on f1 is blocked by his pawn on f4—a common sort of occurrence. What makes it interesting is that the pawn has a way to clear the file and threaten Black’s queen: f4xg5. To make this an effective double attack, of course, White needs a target for his rook once the pawn moves off the file. We look for ways to involve the enemy king, especially when it is so close to the relevant line. Can it be moved from e8 to f8 or f7? The obvious way to move a king is with a check, but here White has none. Another way is to plant a piece on the square where you want the king to move—making either a threat or a capture of your own in the process—and invite it to capture. The one way White can do this is with Nf7. This forks Black’s queen, bishop, and rook (the latter piece is loose), and so requires Black’s immediate attention. His only way to capture the knight is KxN, after which White has the discovered check f4xg5, winning the queen with the pawn whether it stays where it is or moves to f6 to block the check.

So how do you clear pawns from a file? The answer is the same for your pawn and for your opponent’s: they have to make captures. One way to force that result is to take something a pawn protects; but another, useful here, is to simply place a piece en prise to the enemy pawn in a way that creates a threat and requires the pawn to capture. A check is the best example, and White has one that works in this case: Ng6+, forking Black’s king and queen. Black has to play f7xN. Now two things have happened: the enemy pawn has been cleared from f7, and White’s own pawn on f5 has been given a way to get off that file and make a threat: f5xg6+, which unmasks check by White’s queen and also threatens g6xR. The rook will be lost to the pawn, whether it stays put or moves to f7 to block the check.

Now suppose Black grasps this and so tries to avoid KxN; does he have anything else in reply to the fork White launches with Nf7? Black would like to move the queen out of danger and protect the two loose pieces threatened by the knight. This can be done with Qf6. But then White still wins the exchange with NxR.

Dg480: Black to move

Dg481: Black to move

Dg480: Here is something a little different. You're playing the Black pieces. White threatens your h5 rook with his bishop. Think offense before defense; find the kernel of a discovery. Your rook is aimed at the enemy king and masked by the pawns on h4 and h2. You study the king’s position and see that its only flight square (g1) is sealed off by your bishop. Play on the h-file might be indicated, but how? There isn't yet any way for the pawn on h4 to vacate the file, and then there still would be a White pawn on h2. Both problems would be cleared up, however, if the h2 pawn could be goaded onto g3; then it would be out of the way and the Black pawn on h4 would have something to capture. So plant a piece vulnerable to the pawn on h2, and do it with a threat: Ng3+, a fork of bishop, rook, and king. (If that line of reasoning was too cumbersome, try a simpler one: examine any checks you can give and arrive at Ng3.)

Dg481: A queen or rook on a rank where it is masked by a pawn is a good setup for a discovery; if the pawn moves (whether forward or diagonally), the attack is unmasked. Here Black's queen is on a5, masked by his pawn on d5. The pawn can’t advance on the d-file, but it can make a capture on c4, thus clearing the queen’s path across the fifth rank and also launching an attack of its own on White’s d3 bishop. All that needs to be considered is the queen’s target. White has a bishop on g5. It’s not loose, so if the queen were unmasked it wouldn’t be able to make the capture. But the bishop’s only guard is the knight on f3, and a piece that is protected only by another piece often can be weakened or left loose by a preliminary exchange—a capture of the guard, or a capture of the target that requires its guard to recapture and then be left loose. Here Black thus starts by taking the bishop with NxB. NxN follows for White—but now he has a loose piece on g5. Black plays d5xc4, winning material no matter what White does.

So now consider White's replies. If he plays QxN, fine; Black has h4xQ. But what if White replies h2xN? Black plays the discovered check h4xg3. It isn't quite mate because White still has BxR. But now look for Black’s next possible check. It’s Qh4—and this time it is mate, since Black’s bishop still seals off the king’s only flight square. It’s a lesson in the importance of noting how all of your pieces bear on a position and might be brought into the fray. The queen’s path from its starting square to the side of the board (and thus down the h-file) is a potent resource.

Dg482: White to move Dg482: Of course White can simply take a piece here with QxN+, and the temptation to play that move would be sore. But pause be-

fore playing even such obviously attractive moves to make sure you have nothing even better. In this case it's especially important because Black’s king is both exposed and constrained; this can lead to trouble for him in countless ways. The experiments begin by looking at checks you can give and finding Qf4+: safe checks you can give with your queen always need to be examined with care. This one forces Black to play his king to h5. Look for your next check. Follow-ups with your queen either lose the piece or are inconclusive, but don’t forget your pawns: White has g2-g4+. Black’s pawn on f5 can’t very well be used to recapture, as it now is pinned to its queen, so Black’s king is forced back down to h4 (h6 is under attack). See the resulting pattern in your mind’s eye: the king ends up in the same position where it starts, but now White has a queen on f4 and a pawn on g4—the kernel of a discovered check on the fourth rank. White simply steps the pawn forward to g5, forcing the reply Kh5 and winning the queen (g5xQ) next move. The position is a final illustration of a valuable skill: the ability to see possible discoveries arise during the forced sequences you imagine. You think of a check, then your next one; but do you notice that one of your pieces has moved in front of another, making a new sort of threat possible? Consider this batch of studies—and this last one in particular—a way to build your instinct for that pattern.

3.4.5. Strategy and the Discovered Attack. Mastering the discovered attack partly is a matter of getting to know each of your pieces again—as maskers of attacks by other pieces. Thus you may at first think of the bishop as a piece that attacks along diagonals and create double attacks of the sort we saw in the chapter on bishop forks. That’s accurate as far as it goes, but another part of the bishop's power comes from its ability to unmask attacks along files and ranks by rooks and queens. When you look at a bishop you want to see more or less automatically not only where it is aimed but also whether any heavy pieces lie on the rank or file where it resides. You likewise want your eyes trained to notice when a bishop or queen lies on the same diagonal as one of your rooks; and when a rook, bishop, or queen lies on the same line with one of your knights; and when one of your pawns conceals a bishop on its diagonal or a rook or queen on its file. You get the idea: sensitize yourself in general to alignments of your pieces and your opponent’s pieces—both on the board in front of you and on the board as it would look after one or several moves in a series you imagine. Noticing alignments is the key to seeing chances for discovered attacks. It also is the key to seeing chances for pins and skewers, as we will learn in more detail in the next section. The execution of a discovery is a climactic moment during a game; on most of your moves you will have no such opportunity. So what do you do then when you have no way to win material with tactical strikes? You play strategically, making positional moves that increase the strength of your pieces and make eventual tactical shots more likely. From our studies of discovered attacks we can infer some lessons about sound strategic play: the significance of open lines; the usefulness of centralizing your pieces; and the importance of a king’s vulnerabilities. Each of these considerations can be seen from an offensive or defensive standpoint, but for present purposes we mostly will look at them from an offensive point of view.

Discovered checks by bishops require, first, open lines for the rooks and queens that the bishops unmask—in other words, lines unobstructed by pawns. Think first about open files. Rooks depend on them; one thing you learn early in chess is that as powerful as rooks seem to be, they usually do little good so long as they sit behind pawns (unless the pawn is on its way to promotion, but set that possibility to one side for now). Moving a rook to an open file thus vastly increases its strength. Another thing you soon notice is that getting two rooks onto the same open line multiplies their powers further. The point of our studies here is that discovered attacks are still another way to play on open files. You can put a bishop or knight there in front of your rook or queen, or in front of the squares where your rooks or queen may go; in this way you create potential energy on the file, as you have the makings of a double attack of the discovered variety if targets can be brought into view at both ends. The same goes for diagonals. You can play on a diagonal not only by putting a bishop there or a bishop plus a queen, but also by putting a rook or knight in front of those pieces. The rook or knight can't travel on the diagonal, of course, but can jump from it and thus create two attacks at once: the tactician’s dream. Once you appreciate the great uses of open lines, the next question is how to create them. It’s all about pawns. If there are no open files and diagonals, your job is to create them through pawn warfare. Often a pawn move or exchange will be most significant because it will open a file halfway (eliminating one of the pawns on it) or completely (eliminating both pawns), leaving it open for occupation and domination by a rook. Pawns also determine whether diagonals are available for your bishops, whether to create forks or pins or— here—discoveries. This is especially true when either side has a cluster or “phalanx” of pawns, as pawns so arranged will tend to sit on squares of the same color; that is how they protect each other. Their arrangement will determine whether the bishops that travel on those squares will be active or inert. The lesson is to think about the implications of pawn

moves and exchanges for the mobility of your rooks and bishops—and those of your opponent. So getting your pieces onto open lines is one way to create a fertile environment for discoveries. Another element is centralization — establishing pieces near the middle of the board. A discovery requires an arrangement of three pieces: an attacker, a target, and a piece of yours that lies between them and that can leap out of the way. We have seen lots of ways those pieces can be arranged; they all can be clustered at one end of the board, or two can be at one end and one at the other. But in general a knight is most likely to be in position to unmask an attack by another piece when it is more or less centralized, for when it is near the middle of the board it has the best chance of ending up between a friendly and an enemy piece. The same principle holds for most of other pieces when acting as unmaskers. Rooks need lines unblocked by pawns before they can be unmasked and threaten anything. But if a rook is going to unmask an attack by a bishop, it needs more than an open line; it needs to get out onto the board where it can get in front of a bishop or queen. Finally there is the matter of targets. We have seen many times that a good place to start looking for tactical opportunities is the enemy king's position: its exposure, ways that it can be forced to move, or that lines toward it can be opened. The point of the investigations is not necessarily the thought of checkmate, which may be nowhere in sight. The point is that double attacks of all kinds—including discoveries—work best when the enemy king is at one end of them because your opponent’s choice of replies is then so limited. The point has several implications for strategic play. One is the value defensively of castling early, and the advantage to be had if you can prevent castling by the other side. Disrupting the pawn cover in front of the enemy king likewise can have great value, as the king then becomes more exposed as a target at one end of discoveries you may arrange (as well as forks and pins). There are lots of ways to ruin a king's pawn cover; some of them

involve sacrifices, usually as a run-up to a tactical blow you have planned. But on occasion you may be able to tear the cover apart without a sacrifice, and without any particular follow-up in mind, just by forcing exchanges of pieces that are protected by the pawns in front of his king, or by sending your own pawns forward to harass those of the enemy. Another related point is the value of coordinating your pieces to create pressure on the enemy king’s position. This is not always the best strategy; sometimes the king’s position is secure and your advantages lie elsewhere on the board. You make plans in the sectors where you have the best promise of success. But offensive pressure against the enemy king can create prospects for all kinds of tactics that involve busying your opponent with threats in one place while you also create simultaneous threats elsewhere. Forks are one example; discoveries are another. And having pieces coordinated—i.e., aimed at the same area of the board, or otherwise supporting each other's work—tends to be a lot more valuable than having them fire in different directions, in part because their powers can then be combined to make those tactical shots work. Maybe one piece makes a sacrifice to set up a target for another; maybe two of them combine to create a mating threat while also making a threat elsewhere; maybe one can mask and unmask the other.