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.
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.
On the other hand an ending with Bishops of different colour leads mostly to a draw, frequently even against a majority of two pawns. The position in Diagram 75 is a draw, because it is impossible for the White King to get round his Kt pawn to drive off the Bishop.
Diag. 75