opening the line of his Rook and thereby attacking the pinned
Knight for the second time. This threat cannot be effectively
countered. Black could try to unpin the Knight by (5) .... K-g7;
(6) P-f4, Q-e8. Indeed, Black saves his Knight in this way, but
the exposed position of his King leads to a speedy disaster. For
instance: (7) Pxe5, Kt-h7; (8) B-f6+, Ktxf6; (9) Pxf6+, K-h7;
(10) Q-h5+, K-g8; (11) Q-g6+, K-h8; (12) Q-g7+/-. Black could not
take White's Queen on the 11th move because the Pawn f7 was
pinned by the Bishop c4.

If Black had moved his King to g8 or g6 on the 8th move instead
of taking the Bishop f6, White would have forced the mate by
sacrificing his Rook on f5, thereby cutting off the Bishop c8 and
giving his Queen access to the square g4.

Sacrifices with the view to utilizing a pin occur in various
other versions which are essentially different from the one
illustrated above. Following are typical examples of the three
most frequent cases.

In the position of Diagram 38 Black must not take the Pawn e4
although he can protect the Knight with B-f5 in case White pins
him with R-e1.

+---------------------------------------+
8 | #R | | #B | | #K | | | #R |
|---------------------------------------|
7 | #P | #P | | | | | #P | #P |
|---------------------------------------|
6 | | | #P | | | #Kt| | |