Separated Passers: Why Three Files Beat the Rook

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

Our position "Rook Against Separated Pawns" teaches a number: four files. With pawns on b2 and g2, the rook shuttles along the first rank, covers both queening squares, and holds the draw with no help from its king at all.

Move one pawn a file closer and the rule dies. With the pawns on c2 and g2 there are only three files between them. The rook can still reach both first-rank squares, but not in time, and the defence collapses.

Do not promote early. c1=Q is a draw. The queen is simply taken and the surviving pawn is not enough. Bring the king first with Kf2.

Then take the real queen. g1=Q wins; every underpromotion is only a draw. After Rxc2+ the king steps to e3, and queen against rook wins.

The lesson. A rule of thumb with a number in it is a rule with a boundary. This is the position on the other side of the boundary, and it is worth knowing precisely where the line falls.