Boden's mate

Boden's mate uses two bishops on diagonals that cross around the king. One bishop gives check, while the other controls the diagonal squares through which the king might escape. The defender's own pieces, often a rook and another piece or pawn, occupy the remaining exits. It is mate only if no defense can capture the checking bishop, block its diagonal, or free a safe square.

The pattern often appears against a king that has castled queenside, meaning it moved two squares toward the rook on the queen's side while that rook crossed to the other side of the king. In that location the king is commonly close to its own pieces and to diagonals that captures can open.

Many well-known combinations deliberately give up the queen on c3 or c6 to force a pawn to capture and clear the diagonal of the bishop that will mate. This method is frequent but not required. The essential features are the bishops' crossing geometry and the elimination of every remaining escape square.

Boden's mate should not be confused with the basic king and two bishops against king ending. That endgame requires the attacking king to drive the lone king gradually toward a corner. Boden's mate is a concrete tactical pattern in a position with more pieces, where the defending army helps confine its own king.