|---------------------------------------| 4 | | | | | | | | | |---------------------------------------| 3 | | | | | | | | | |---------------------------------------| 2 | | | | | | | | | |---------------------------------------| 1 | | | | | | | | | --------------------------------------- A B C D E F G H

Diag. 73

pawn were still at R5, White’s King could attack the pawn from R6 and secure the win.

In the position given, White could only win by keeping his passed pawn, and indeed it is possible to win by gaining a move with the Bishop.  In the diagram it is White’s move.  Black with the move could not play K-B2 because K-Q6 would follow.  The Knight would have to move, allowing the pawn to queen.  Therefore White must try to bring about the same position with Black to move.  He can do this, for instance, in the following way: 

1.  B-Kt3, K-B2 (now 2.  K-Q6 would be bad on account of Kt-Q5, 3.  P-B7, Kt-Kt5ch, and KtxP); 2.  B-R2, K-K2; 3.  B-K5.  Now White’s plan has succeeded; the same position has occurred, and it is Black’s move.  As mentioned before, the King must not move, but Knight’s moves are of no avail.  If 3. ...  Kt-Kt4; 4.  B-B6ch, the Knight is lost, or alternatively the pawn queens.  On 3. ...  Kt-B1, B-Q6ch decides, and on 3. ...  Kt-Q1; 4.  B-B6ch, K-K1; 5.  BxKt would follow.

On this occasion I should like to point out that it is impossible to gain a move with a Knight, as a square which is accessible to him in an odd number of moves cannot be reached by him in an even number.  A simple instance is Diagram 74.

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8 |    |    |    |    |    |    |    |    |
|---------------------------------------|
7 |    |    |    |    |    | #K |    | ^K |
|---------------------------------------|
6 |    |    | ^Kt|    |    |    |    | ^P |
|---------------------------------------|
5 |    |    |    |    |    |    |    |    |
|---------------------------------------|
4 |    |    |    |    |    |    |    |    |
|---------------------------------------|
3 |    |    |    |    |    |    |    |    |
|---------------------------------------|
2 |    |    |    |    |    |    |    |    |
|---------------------------------------|
1 |    |    |    |    |    |    |    |    |
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A    B    C    D    E    F    G    H

Diag. 74

White loses, having the move. 1.  K-R8, Kt-K4; 2.  K-R2, Kt-Q2; 3.  K-R8, Kt-B1; 4.  P-R7, Kt-Kt3 mate.

Black with the move cannot win, as he cannot bring about the same position with White to move.

In end-games of bishop V. Bishop, of which we have already had an example in Diagram 70, an extra pawn wins in most cases if the Bishops are of the same colour.  It is generally possible to force an exchange of Bishops and obtain one of the well-known pawn endings.