Triangulation is an endgame king manoeuvre in which the king walks around three squares forming a triangle in three moves and returns to its starting square. The result is the same position on the board, but with the opponent to move.
Why it is needed
Pawn endgames often feature mutual zugzwang: whoever has to move loses. If such a position arises with you to move, it would be nice to “pass” — but the rules do not allow it. Triangulation solves the problem: the king spends an extra move, and the opponent cannot do the same.
How it works
The manoeuvre is possible when your king has more freedom than the opponent's:
- Your king can move around three adjacent squares forming a triangle while keeping all its duties (for example, protecting a pawn).
- The opponent's king is tied to two squares: it can only shuttle back and forth.
- You go round the triangle in three moves; in the same time the opponent makes three moves between two squares — and ends up “out of phase”.
After that the position repeats, but now it is the opponent's move, and they are in zugzwang.
Where it occurs
- In king and pawn against king and pawn endings.
- In positions where you need to take the opposition but the opponent holds it.
- In queen against pawn endings and some rook endgames.
A tip
Triangulation is hard to grasp from a description: take a board and work through the topic with a coach on concrete positions. First get a firm grip on the opposition and the rule of the square.