Cutting Off the King in Rook Endgames

Watch the method: press play to see the winning idea run, or step through it move by move.

Rook and pawn versus rook is a draw when the defending king reaches the pawn's path, and usually a win when it does not. That single sentence decides more endgames than any other, and the tool that enforces it is the cutoff: a rook parked on the file between the enemy king and your pawn.

Why a file and not checks. Checks push a king around for a move or two, but a king can walk through a rain of checks toward the pawn. A rook on a file is different: the king can never cross it, because every crossing square is covered forever. One rook move buys a permanent wall, and the fight is over WHERE the wall stands.

The conversion. Behind the fence, advance the pawn with its king beside it. The defending rook will harass from behind or from the side; answer by keeping your king close to the pawn and using the pawn itself as shelter. The endpoint is a Lucena position, which you already know how to win.

The rule of thumb: a pawn on the fourth rank or beyond wins if the defending king is cut off by one file; farther back it needs a wider cut. In this drill the geometry is exactly on the boundary, and a defence that never cracks will test every attempt to relax the fence.