Sacrifices made with the view of a direct mating attack are, as a rule, the easiest to figure out, as there is no guesswork connected with them.  In those cases the player does not face the question as to whether the position attained after the sacrifice will be strong enough to insure a gain of material at least equivalent to the amount of material sacrificed, a question which to answer correctly sometimes requires a good deal of instinct trained by experience; all that is necessary if to ascertain whether the opponent can be mated in a definite number of moves or not.  If the mate cannot be clearly foreseen, the sacrifice must not be made.  The possibility of a sacrifice with consequent forced mate is always indicated if a greatly superior force is available for attack at the part of the board where the opposing King is located.  An example is offered by the position reproduced on the book cover.

  [E-text editor note:  The position on the book cover is: 

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

This position occurred in a game between Sir G. A. Thomas of London and the author.  Black has just played Q-e7 in order to protect the mate which was threatened by Ktxf6+ followed by Qxh7.  If in the position of the diagram White played Kt-f6+, Black would retake with the Pawn, thereby protecting the Pawn h7 with his Queen.  However, White can force the mate with a neat Queen’s sacrifice which drives Black’s King right into the arms of the remaining White pieces.  Play continued as follows: 

(1) Qxh7+         Kxh7
(2) Ktxf6++       K-h6

The King cannot go to h8 on account of Kt-g6 mate.  White now continually checks Black’s King in such a manner that he has only one square to go to until he is finally driven to the first rank, all White pieces participating in the chase.

         (3) Kte5-g4+

In answer to Ktf6-g4+ Black would play K-h5; (4) B-g6+, K-h4; (5) P-g3+, K-h3 and there is no mate.

(3) ...  K-g5 (4) P-h4+ K-f4 (5) P-g3+ K-f3 (6) B-e2+ K-g2 (7) R-h2+ K-g1 (8) K-d2 mate.

White could have forced the mate in seven instead of eight moves by playing (6) K-f1, or (6) o-o, for there was no protection against (7) Kt-h2.