Moving the King into Position, etc

As you no doubt are noticing, the tools re-quired 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 loos-ening 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 at-tacks 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 involv-ing 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, how-ever, 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 de-veloping some new habits. If you are not an experienced player you probably are accus-tomed 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 fol-low. 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 analyti-cal 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 diago-nal 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 pro-tected.) 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 bish-ops attack? (Not what can they capture, but what can they threaten by moving.) Bf5 at-tacks 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 light-squared 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 remember-ing 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 tacti-cal possibility is to note the classic king-and-rook 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 re-quires 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.

Dg232: 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 ap-pealing 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 dou-ble 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

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

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 dou-ble attack against the a5 rook and against ei-ther 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.

Dg233: White to move

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 at-tacking anything else. Still, the sight of the bishop attacking an enemy piece while also aimed at h7 should stimulate your imagina-tion. 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.

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 de-scribed; 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).

Dg234: Black to move

Attacking the rook with Be4 has the interest-ing result of also attackinterest-ing 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 move-ments. 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

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 ex-change 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.