En Passant

The en passant capture is a move in chess. It consists of using a pawn to capture a horizontally adjacent enemy pawn that has just advanced two squares in one move. The capturing pawn moves to the square that the enemy pawn passed over, as if the enemy pawn had advanced only one square. Such a capture is permitted only on the turn immediately after the two-square advance; it cannot be done on a later turn.

The en passant capture was introduced due to the introduction of the pawn's two-square move. It exists so that a pawn cannot evade capture by skipping a square attacked by an enemy pawn.

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