Bishop and Knight versus King

Overview

Bishop and knight against king is a forced win, but it is the trickiest of the basic mates: from the centre it can take over thirty accurate moves. The defining constraint is that the mate must be delivered in a corner whose colour matches the bishop's diagonal — the wrong corner cannot be mated in.

The right corner and the W maneuver

First push the defending king to any edge, then walk it along the edge to the correct corner. The knight performs its famous W-shaped path — a5–b7–d6–f7 type jumps — cutting escape squares the bishop cannot reach. Every move should shrink the box; a single careless knight retreat can let the king back to the centre.

The final net

Near the corner the pieces lock in: the knight covers the escape on the edge, the bishop takes the checking diagonal, and the king closes the last file.

Practice positions

Play each position out against the engine from the exact spot on the board — unrated, you take the strong side.