Figure 6.2.13.6[White to move]

Here are some similar ideas. White executed the usual bishop sacrifice on h7 and then moved his knight to g5 with check; Black replied by moving his king to g6. White’s h-pawn is not yet advanced, but his strongest move is to play it to h4. The point is not to protect the knight, which is in no immediate danger. The point is to play h4-h5+ next turn. Notice that once Black’s king is on g6 its mobility becomes limited, so you may be able to get away with moves like this pawn push, which builds a threat without giving check. At the same time, since you are not giving check your opponent has more choices of reply, and those choices will affect how you can follow-up—which is why it is hard to be precise about how to play these situations. If Black is imprecise he can get mated here; if he replies to h4-h5 with Kf5, for example, the game ends with g2-g4# as seen a few moments ago.

If Black instead plays his king to h6, there are several ways things can go; as usual, the best we can do is suggest possibilities. White can bring in his queen at g4, which usually is a good practice before unleashing a discovered check (with your bishop) by moving the knight from g5. Once that knight moves, Black can retreat his king to h7 and then g8; you want to keep the king stuck out in the open for a move or two so you can rally more firepower to the scene. Having the queen close by gives White lots of ways to threaten mate by combining it with the knight or bishop or with a pawn. Once White then discovers check by moving his knight, the knight becomes a possible forking threat; plus the h-pawn can be advanced to create mating threats with the queen; etc.

To take a concrete variation, suppose that in the pictured position White plays 1. h4 and Black replies Qe8, removing his queen from the danger of being forked by White’s knight after Black has to move his king to h6. Sure enough, 2. h4-h5+, Kh6 follows. Now 3. Qd3 (threatening Qh7#), Nf5 (interposing); 4. g2-g4 (threatening Black's knight), f7-f6 (threatening your knight); 5. Nxe6+ (discovering check and attacking Black's rook), NxB (extinguishing the check but losing the exchange next move).

This position concludes our brief treatment of the h7 sacrifice. Again, its purpose has just been to give you a flavor of the various ideas that typically can come into play when the pattern is triggered. There is a good deal more to this mating idea than has been shown in this introduction—more sub-patterns and details. If you are interested in pursuing it further, Vukovich’s The Art of Attack has the leading discussion.