Philidor position

The Philidor position is a fundamental defense in a king, rook, and pawn versus king and rook ending. The defending king stands in front of the pawn near its promotion square. The defending rook maintains a barrier on its third rank, counted from the defender's side, while the pawn has not yet reached that rank.

The third-rank defense

1. Keep the king in front of the pawn to stop promotion and guard the entry squares.
2. Move the rook along the third rank, preventing the attacking king from crossing the barrier.
3. Wait until the pawn advances to the attacker's sixth rank. That push removes shelter from its own king.
4. Drop the rook to the back rank and check from behind. The attacking king can no longer hide without leaving the pawn.

The timing of the switch is the critical point. If the rook leaves the third rank too early, the attacking king may penetrate. If it waits after the correct pawn advance, it may lose checking distance. The defense also fails if the king is driven away from the pawn's front.

Philidor aims to secure a draw before the attacker reaches a winning structure such as the Lucena position. It is not a rule for every arrangement: the pawn rank, rook activity, and both king positions must satisfy the method's conditions.