Two Bishops vs Knight: the Kling and Horwitz Position
White to play and win, after Kling and Horwitz, 1851
PlayTwo bishops beat a lone knight almost every time. Kling and Horwitz gave this position in 1851 as a draw: the knight on b7, right next to its king, is very hard to attack. In 1983 computer analysis showed that White wins, because the setup can be broken without letting Black rebuild it in another corner. With perfect play on both sides, the tablebase gives mate in 57 moves. You play to win one thing, the knight: once it falls, the usual two-bishop mate finishes the job.
Updated
New to this ending? Learn the method first: How to Checkmate in Chess
No signup needed. The opponent never gives up, and every mistake gets explained.
Kling and Horwitz: Two Bishops Against a Knight
White to play and win · Win against perfect defense
Waking the engine…
The theory
Watch the method: press play to see the winning idea run, or step through it move by move.
Two bishops beat a lone knight in nearly every position. This one was taken for the exception, and it took chess 132 years to settle.
A draw for 132 years. Kling and Horwitz gave this position in 1851 and assessed it as drawn. The knight on b7 sits right next to its king, covering the squares the bishop pair needs, and no human analysis could crack it. Only in 1983 did computer analysis show that White wins.
Why it is so hard. The defense is not one fortress, it is a family of them. Even after you break the setup in this corner, Black tries to reassemble the same king-and-knight formation in another. The winning method has to destroy the b7 construction without letting it be restored anywhere else on the board.
The fifty-move problem. The tablebase gives mate in 57 moves, which is past the fifty-move limit. What rescues the win is that the knight falls first: the capture zeroes the counter, and what is left is the standard two-bishop mate, which does work in any corner.
In this drill the defender holds the fortress without cracking and will not hand you the knight. Take away its squares with the bishop pair, walk your king in to remove the flight squares, and be patient. This is the hardest two-bishop win there is.