Clearing the Path to the Forking Square

Dg138: 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.

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 at-tacked; White forces the king to move by tak-ing somethtak-ing that only it protects.

Dg140: White to move

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 ar-ranged for a queen fork with Qc2+, gaining White a pawn.

2.2.8. Clearing the Path to the Forking Square.

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 ex-change.

Dg141: 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 princi-ple 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 inacces-sible). 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 some-thing 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 f3-f4 is Qh5, allowing him to reply to f3-f4xB with f6xe5.)

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.

Dg142: White to move

Dg142: Again, start by looking for the ingre-dients of a double attack. Black has a loose rook at a8: a good target if you can take ad-vantage 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 pro-tected 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 ex-changes. 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.

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 se-quence.

Dg145: Black to move

Dg145: The analysis here sounds almost the same as in the previous frame. Start by look-ing for the look-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 posi-tion 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

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.

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!

Dg147: White to move

Dg147: White is behind in material and needs to make something happen. Step 1: Experi-ment 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 be-cause the connection between Black’s rooks has been broken by his king. More impor-tantly, 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.

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 po-sition, 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 ma-terial. But this won’t stop you from experi-menting with the move so long as you re-member 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 be-come 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.