Triangulation
A king manoeuvre using three squares to lose a tempo and pass the obligation to move back to the opponent.
Triangulation is an endgame technique for losing a single tempo by walking your king in a triangle. The same position is reached as before, but now the opponent is on move instead of you. If the position is one of mutual zugzwang, this is decisive — you have transferred the obligation to move back to the opponent, and their forced move loses.
The classic example is a king-and-pawn endgame where direct opposition is not enough. Your king on c3 wants to advance to b4 or d4, but the opponent’s king on c5 holds the opposition. Instead of pressing directly, your king walks to c2, then b2, then back to c3 — three moves, three squares. The opponent’s king cannot match the manoeuvre (because their pawn position constrains them) and must give way.
Triangulation works because chess has no pass. A side that is one tempo ahead in king position usually wins; a side that needs to lose a tempo must do so by walking pieces in patterns that don’t change the structure but do change whose move it is. The triangle is the smallest such pattern.
Knight triangulation is rarer and more exotic — knights can sometimes return to a square in three moves (knight on b1 → d2 → b3 → b1), but the practical applications are few. King triangulation is the everyday tool, and any serious endgame study includes it as a basic technique.