(1) Kt-g5          o-o
(2) Q-h5           P-h6

This is the only defense against the threat Qxh7 mate.  But White’s Queen’s move involved a double threat.  It brought up a third attack on the Pawn f7, and the latter now falls, forcing Black to give up some more material.

          (3) Ktxf7 Rxf7

Black has to sacrifice the exchange.  If he moved the Queen, which is attacked by the Knight, he would expose his King to a deadly double check, viz.:  (4) Ktxh6++, K-h8 or h7; (5) Kt-f7+ (discovered), K-g8; (6) Q-h8 mate.  After giving up his Rook for the Knight on the third move Black has a lost game, for as explained in the previous chapter White can simply exchange all pieces and force the win in the ending with his superior material.

Another square which after castling on the King side is often the mark of attack for the Queen in connection with either Knight or Bishop, is the one immediately in front of the King in the Knight’s file.  Diagram 26 illustrates several possibilities of this kind.  White, on the move, can play (1) Q-g5, attacking for the second time the Pawn g7 which is only once protected.  The threat, however, is not only to win a Pawn, but to win the game, for in taking the Pawn with the Queen White would checkmate Black’s King.

+---------------------------------------+
8 | #R |    |    |    |    | #R | #K |    |
|---------------------------------------|
7 | #P | #P | #P |    |    | #P | #P | #P |
|---------------------------------------|
6 |    | #B |    | #P |    |    |    |    |
|---------------------------------------|
5 |    |    | #Q |    | #P | ^Kt|    |    |
|---------------------------------------|
4 |    | #Kt|    |    | ^P |    |    | ^B |
|---------------------------------------|
3 |    | ^P |    | ^P |    |    |    |    |
|---------------------------------------|
2 |    | ^P | ^P | ^Q |    | ^P | ^P | ^P |
|---------------------------------------|
1 | ^R |    |    |    |    | ^R | ^K |    |
+---------------------------------------+
a    b    c    d    e    f    g    h

Diagram 26

The only defense at Black’s disposal is P-g6, but this move helps only temporarily.  White can force the mate within a few moves in different ways.  One would be the following: 

(2) Kt-h6+ K-g7

If the King goes to h8 White mates by Q-f6.

          (3) Q-f6+ Kxh6
          (4) B-g5+ K-h5
          (5) P-h3

and the mate through P-g4 cannot be protected.  Another way would be: 

          (2) Q-h6 Pxf5
          (3) B-f6

and the mate through Q-g7 cannot be protected.