Opposition

The opposition is a position in which the kings stand facing each other on the same line with one square between them, and it is the opponent's turn to move. The player who made the last move is said to have the opposition: the opponent has to give way.

Kings cannot stand next to each other, so in the opposition neither can step forward. The one who has to move must step aside — and let the other king through.

Kinds of opposition

• Direct — the kings on the same file or rank with one square between them (for example, e4 and e6).
• Diagonal — on the same diagonal with one square between them (e4 and g6).
• Distant — on the same line with three or five squares between them. It is “converted” into close opposition as the kings approach.

The opposition in king and pawn against king

Here the opposition decides whether the stronger side wins or it is a draw.

Here White would win even with White to move: the king already stands on the sixth rank in front of the pawn. But shift everything one rank down — white king e5, pawn e4, black king e7 — and the side to move decides the outcome. With Black to move White has the opposition and wins. With White to move Black takes the opposition, and with correct defence it is a draw.

A rule for pawn endgames

• The stronger side's king should stand in front of its pawn.
• If the king is on the sixth rank in front of the pawn (not a rook's pawn), it is a win whoever is to move.
• If the king stands in front of the pawn on the fifth rank, the result depends on the opposition.

The opposition is a special case of zugzwang: the opponent is forced to make a move that worsens their position. Another way to pass the move is triangulation.