Philidor position

The Philidor position is the most important defensive technique in rook-and-pawn endgames. The attacker has king, rook, and pawn; the defender has king and rook. The defender’s task is to prevent the attacker’s king from advancing far enough to support the pawn’s promotion.

The technique: the defender places his rook on the third rank (from his own side of the board — that is, the rank three squares in front of the attacker’s pawn). The defender’s rook patrols this rank horizontally. The attacker’s king cannot advance past this rank, because doing so allows the rook to deliver check from behind once the attacker’s pawn advances to the sixth rank. The defender does not check; the defender’s rook just sits and waits.

When the attacker finally pushes the pawn to the sixth rank, the defender moves his rook down to the first or second rank and gives checks from behind. With the attacker’s king now exposed, the checks cannot be blocked without losing the pawn. The defender draws.

Philidor — François-André Danican Philidor — was the eighteenth-century French master who first analyzed this position systematically. His treatise L’Analyse des Échecs (1749) remains a foundational text. The position’s name has stuck for two and a half centuries, and the technique is still taught in every basic endgame curriculum.