Two knights cannot force a checkmate, but a bishop pair or a bishop and a knight can.

Though difficult, checkmating with a bishop and a knight is not only possible but also presents a real test of a player’s ability to coordinate the moves of those two pieces. The bishop-knight checkmate has to be delivered within the fifty-move draw limit without repeating a position three times or reaching a stalemate.

The bishop-knight mate is accomplished in three steps:

1. Force the king to the side of the board,
2. Force the king out of the wrong color corner, if required, and
3. Deliver mate with the bishop in the lethal colored corner, the color of the bishop.

The last two moves in the forced mating sequence are checks, delivered first by the knight and finally by the bishop.

In the example below, White forces mate with a white bishop, so the “wrong colored” corner squares are black. The mating squares, of course, are the two white corners where White’s white bishop is deadly.

Since White’s bishop can only cover white squares, the king and the knight have to cover the black squares in the mating sequence.

If you play on with only the king, against the bishop and knight, try to keep the king in the center of the board away from a side or corner as long as possible. Once the king is driven from the center of the board, try to reach the wrong corner of the board; in this case it’s a black corner since the king can only be mated on a white corner square. However, if the king missteps, checkmating on other squares is also possible. I point out one such instance in the following mating sequence.

With best play from any board position, the bishop and knight should be able to mate in 34 moves. To simplify the discussion, here is an end game with the Black king, already at the side of the board, on the “wrong color” corner square. Once you master mating with your opponent’s king on the side of the board, a logical next step would be to practice forcing the king to the side of the board using the king, the bishop, and the knight.

To get the most out of this discussion set up the following position:

White to Move

1. Nf7+ Kg8

White begins with a knight check; Black’s king move is forced.

2. Ba4 Kf8

White’s bishop maintains control of e8.

3. Kf6 Kg8

White’s king covers e7; Black’s king heads away from a8.

4. Bc2 Kf8

White’s bishop covers h7.

5. Bh7 Ke8

White’s bishop covers g8.

6. Ne5 Kf8

White’s knight covers d7; Black’s king heads away from square a8.

7. Nd7+ Ke8

White’s knight now covers f8; Black’s king has to move closer to a8 again

8. Ke6 Kd8

White’s king maintains opposition and guards the knight.

9. Kd6 Ke8

White’s king maintains opposition; Black’s king heads away from square a8.

10. Bg6+ Kd8

White’s bishop gains control of e8.

11. Nc5 Kc8

White’s knight takes control of b7

12. Bf5+ Kd8

Black’s king heads away from a8.

13. Ne6+ Kc8

If 13...Ke8 14.Bg6#.

14. Kc6 Kb8

White’s king maintains opposition to limit Black’s king movements to only two squares.

15. Nc5 Ka7

White’s knight controls a6 to corner Black’s king.

16. Kc7 Ka8

Black’s king is limited to two squares though a different two.

17. Kb6 Kb8

White’s king guards a6 from where White’s knight will check.

18. Na6+ Ka8

“Gotcha!” says White.

19. Be4#

Although the bishop-knight mate can be forced, it is difficult to achieve over the board within the fifty-move (with out a pawn move or a capture) draw limit. If the bishop or knight is captured, White can no longer win and has to accept a draw.

With the bishop and knight against a bare king, you have at least a tie. If you have time on your clock, play the game out to a win or a fifty-move draw. If you are short of time, your opponent can achieve no more than a draw if your flag falls.

Playing as White, you have at least achieved a draw no matter what happen in the rest of the game. The bishop-knight is a tough win, but it is possible if you know the winning technique. I hope that you have learned it here.