This is especially true of the mating positions which are discussed below in connection with attacks instituted by the Queen in the middle of the game.  It is these attacks to which the beginner at an early stage of the game falls victim in ninety out of a hundred cases when playing against an experienced opponent.

In the position of Diagram 20 White on the move wins the exchange and thereby practically the game by playing (1) Kt-d5.  With this move he attacks the Queen and at the same time the Pawn c7.  Black, in order not to lose the Queen, must move her, but he cannot move her so that she will protect the Pawn c7.

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

Diagram 21.

On the next move White will, therefore, take the Pawn calling Check and at the same time attacking the Rook a8.  The King must move and the Knight takes the Rook.

Quite frequently a similar attack with the Knight is likely to win the Queen if the opponent is not familiar with situations of that kind.  If in the position of Diagram 21 White plays (1) Kt-d5, Black must protect the Pawn c7 by Q-d8 or Q-d6, but not by Q-c6; for in the latter case White would continue with (2) B-b5, Qxb5; (3) Ktxc7+ and (4) Ktxb5.

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

Diagram 22.

Sometimes two pieces are involved in the double attack, the line of one of the pieces being discovered by the other.  Thus, in the position of Diagram 22, which could be brought about by the moves (1) P-e4, P-d5; (2) Pxd5, Qxd5; (3) Kt-c3, Q-a5; (4) P-d4, Kt-f6; (5) B-c4, P-e6; (6) B-d2, white threatens to play (7) Kt-d5, uncovering the Bishop d2 on Black’s Queen and at the same time attacking the Pawn c7, which Black cannot keep protected.