Stamma's mate

Stamma's mate is a striking exception: a king and knight can deliver mate because the defending king is trapped in front of its own rook pawn. A rook pawn is a pawn on either outermost file of the board.

Normally, king and knight cannot mate a lone king. Here the defending pawn changes the geometry by occupying or controlling space the king would need for escape. The attacking king limits nearby squares, and the knight gives the final check from the required distance.

King and knight move firstThe pawn side moves first

Check first, reroute afterward

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a1

b

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h

StartNb4+Ka1Kc1a2Nc2#

The pawn on a3 forms a wall for its own king and preserves a2 as a reserve tempo.

The same cage, White to move

The black king is already restricted near the corner. White must use the first tempo without dismantling the cage.

1. The pawn on a3 forms a wall for its own king and preserves a2 as a reserve tempo.
2. The king on c2 keeps b1 and b2 closed.

This is an endgame mechanism, meaning it belongs to the stage in which few pieces remain, rather than being only a static tactical picture. Move order matters because the pawn may advance and change the available squares. Before assuming the mate is forced, calculate whether the attacking king arrives in time and whether the knight can check without releasing the king.