Figure 6.2.15.4[White to move]

Here is another example of how the ideas in this chapter can be used to win material. Again Black has imposed the improvident pin with Bg4; again White walks out of it with 1. NxN. If Black plays 1. …d6xN, fine; White plays QxB, winning a piece. But if Black tries 1. …BxQ, White has Bb5+, and now Black can avoid mate only by interposing his queen on d7. White takes it with his bishop and gives check with it at the same time. (He could take it with his knight instead, but it wouldn't give check and wouldn't work as well afterwards for reasons we will see in a moment.) As an exercise, let me invite you to consider what happens next (after White has played BxQd7+).

Done? All right: Black can't recapture on d7 with his king because the square is guarded by White's knight from e5. He has to play Kd8. Now White has Nxf7+. It leaves his bishop unguarded, but that's okay; for the move forks Black's king and rook. Black goes ahead with the capture KxB; it's the best he can do. And now does White strike with NxR, carrying out the other end of the fork? No, not quite yet. He doesn't need to do it yet, because the rook is smothered on h7; it isn't going anywhere. Instead White takes the opportunity to play KxB back at the other end of the board. Then he still has NxR still waiting to be played on the next move.

To return to our theme, in a sense the most important function of White’s initial move NxN here was simply to eliminate the Black knight that prevented Bb5 from being effective. The full pattern for Legall’s mate is not quite used here, but it is a typical example of the common sacrificing idea associated with the mate (the “pinned” knight captures on e5).