Zugzwang is a chess term. It means a situation where any move by a player will weaken the player's position. The fact that the player is compelled to move means that their position will become significantly weaker.
- Black to play
1. ... Kd7 and White cannot win:
2. c6+ Kc7
3. Kc5 Kc8
4. Kd6 Kd8 (opposing the king)
5. c7+ Kc8
6. Kc6 is stalemate
- White to play
But if it is White to play in the original position, he can win by zugzwang:
1. Kc6! and now Black must move his king, for example
3. Kb7 and queens the pawn.
Mutual zugzwang[change | change source]
There are positions where either player to move will lose.
On the following diagram, Whichever king moves, he loses his pawn and the opponent will win the game.
History[change | change source]
The term itself comes from the 19th century in a German chess magazine. Its first use in English was in the early 20th century.