a b c d e f g h

DIAGRAM 36.

In the position of Diagram 36 White can make an attack which will
recall somewhat the play shown in connection with Diagram 25. (1)
Kt-g5 would not lead to anything, as Black could defend himself
by P-g6 or P-h6. White has a much more direct way to attack the
black King. This is by the sacrifice (1) Bxh7+. After Kxh7; (2)
Kt-g5+, K-g8; (3) Q-h5 Black can protect the mate only by
sacrificing his Queen for White's Knight. For (3) ..., R-e8 with
the view to escape with the King to e7 via f8 if attacked by Q-h7
and Q-h8 would be rendered futile by White through (4) Qxf7+, K-
h8; (5) Q-h5+, K-g8; (6) Q-h7+, K-f8; (7) Q-h8+, K-e7; (8) Qxg7
mate. Before making the sacrifice of the Bishop White will, of
course, have to make sure that Black cannot save himself by
evading altogether the attack which is threatened through Q-h5.
Black could, indeed, avoid this variation by going with the King
to g6 on the second move instead of g8. But in this case too
White has a winning continuation. He would play (3) Q-g4
threatening to win Black's Queen by the discovered check Ktxe6.
If Black moves the Queen, then White gives the discovered check
in any case forcing the King to h7 and leading over to the
variation which was originally intended. If, on the other hand,
Black tried (3) ..., P-f5, attacking White's Queen and thereby
rendering the discovered check ineffective, White would first
take the Pawn en passant and after (4) Pxf6, Kxf6 the Queen mates
on e6.

Frequently a sacrifice is brought to maintain a pin which is