Dovetail mate
Also known as Cozio's mate
A protected queen mates a king from a diagonally adjacent square. The king cannot flee because two of its own pieces plug its escape squares, which splay out behind it like the tail of a dove - and the queen covers everything else.
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How it works
The queen lands diagonally next to the king (here c5 against a king on d6) and checks along that diagonal. A friendly pawn on b4 guards the queen, so the king cannot capture her. Two of the king's flights are plugged by its own pawns on d7 and e6. The queen sweeps the rest: she covers c6 and c7 up the file, d5 and e5 along the rank, and e7 along the far diagonal. With every exit blocked or guarded and a contact check that cannot be parried, it is mate.
How to spot it
Look for an enemy king hemmed in by its own pawns or pieces, especially in queen endgames or after a cramped castled position has been stripped of defenders. If two of the king's flight squares are already self-blocked and you can drop your queen onto a diagonally adjacent square while keeping her protected, the dovetail is on. The tell-tale shape is the king with two friendly units flaring out behind it.
Key ideas
- The queen mates from a square diagonally beside the king, not in front of it.
- She must be protected - usually by a pawn - so the king cannot take her.
- The king's own pieces block two flights, forming the dovetail shape.
- The queen single-handedly covers all the remaining escape squares.
- Common in queen endings where a king is boxed in by its own pawns.
- Related to the epaulette mate, but with diagonal rather than flanking blockers.
Famous example
The pattern shares its alternative name, Cozio's mate, with the 18th-century Italian theorist Carlo Cozio. It is a staple of queen-and-pawn endgames, where a king boxed in by its own pawns is the classic victim.