Opposition

The opposition is the most basic king-and-pawn endgame concept. Two kings sit on the same file, rank, or diagonal with one square between them. Neither can advance into the other’s square. The king whose turn it is must step aside, allowing the opposing king to advance. The side not to move controls the position and is said to have the opposition.

The opposition is a zugzwang condition. The side to move is forced into a worse king position. In king-and-pawn endgames the opposition decides whether a pawn promotes — the king holding the opposition can shepherd a pawn forward; the king without it must give way.

There are three types of opposition. Direct opposition is the standard case with one square between the kings. Distant opposition keeps the kings on the same file or rank with three or five squares between them — the same principle, longer range. Diagonal opposition applies on diagonals, less common but identical in principle.

Mastery of the opposition is one of the first endgame skills. The pawn endings of Capablanca, Smyslov, and Magnus Carlsen are full of subtle opposition manoeuvres — small king moves that look identical but are not, and that decide whether the position is won, drawn, or lost.