Anastasia's mate

Anastasia's mate occurs against a king on the edge of the board, usually near a corner. A rook or queen gives check along an open horizontal rank or vertical file. A knight controls two squares through which the king would move away from the edge, while one of the king's own pieces, often a pawn, occupies another escape square.

The checking line must be clear between the long-range piece and the king. The rook or queen also controls the edge squares in front of and behind the king, while the knight covers the two inward exits. The position is mate only if no piece can capture the attacker, block the line, or create a legal escape.

Many Anastasia combinations begin by deliberately giving up a queen or rook to force a pawn to capture and open the line. That material offer is a common construction method, not part of the definition. If the rank or file is already open, the mate may be immediate.

In Arabian mate, the rook is usually beside the king and the knight protects the rook. In Anastasia's mate, the long-range piece may be far away, the knight normally controls two exits, and a defending piece completes the confinement.