Making the Forking Square Avail able.

Now that you are familiar with simple queen forks, consider a first way they can become complicated: the square you need—the fork- ing 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 defend- ing a piece that sits on it, or else just protect- ing 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 de- fender recaptures the square is left unpro- tected (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 ex- amples of how it works here.

Dg114: White to move

Dg114: Examine the position using the ap- proach already established: look for ways to combine a check with an attack on an un- guarded 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 chap- ter 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 at- tackers 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.

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?

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 cap- ture the occupant of the square and invite re- capture. The result in either case is the loosen- ing 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 pro- tected by the knight at f8. White can’t capture the knight, and there is no way for him to

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+. No- tice that White’s queen greatly constrains the ability of the Black king to flee such an at- tack; 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.

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 prom- ising 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 ques- tion: 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.

The procedures for handling this sort of prob- lem 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.

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 at- tract your attention and cause you to focus on getting rid of the rook. There are standard tools available for the purpose. A first re- course 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 valu- able 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 g3- g4. If the rook moves to safety, White has the queen fork Qe5+, winning a piece.

2.2.5. Loosening the Target by Exchanging