Opposition

Opposition is a relationship between the two kings, especially important in pawn endings. Kings attack every neighboring square and can never stand next to each other. When they face with the right spacing, the king that must move may be forced aside, opening a route for the other king.

In the simplest form, the player who is not to move has the opposition. The opposing king steps to one side, and the other king can answer by advancing, blocking entry, or preserving the relationship. Opposition is not a winning goal by itself; it is a tool for reaching a concrete objective.

What opposition is used for

• Entering a key square from which a pawn can be promoted.
• Preventing the enemy king from entering and attacking pawns.
• Creating zugzwang, a position in which every legal move worsens the situation of the player who must move.
• Changing routes through direct opposition, distant opposition, or diagonal opposition.

The geometry works only when the route and the relevant squares are available. A pawn may provide a waiting move, meaning a move that preserves the king's task while changing whose turn it is. Another piece may block the path, or the opposition may point toward the wrong side. Always ask which square is gained after the other king is forced to move.