Réti's mate
Also known as Reti's mate
Réti's mate is a bishop mate: a bishop lands beside a king boxed in by its own pieces, a rook on the open file guards the bishop, and the bishop's X-ray reaches through the king to cover the last flight. Here Bd8 is mate – the king on c7 is walled by its own men, the rook on d1 holds the bishop, and b6 is covered through the king.
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How it works
The black king on c7 has no air: its own knight on b8 and bishop on c8 block the back squares, and pawns on b7 and c6 wall off the queenside. White's bishop comes to d8 giving check. The king cannot capture because the rook on d1 defends d8 down the wide-open d-file (which also covers d6 and d7). The one remaining flight, b6, is covered by the bishop's X-ray straight through the king on the d8–a5 diagonal. No piece can interpose against an adjacent checker, so it is mate.
How to spot it
Look for an enemy king crowded by its own pieces with an open file already pointing at the back square beside it. Slot a rook onto that file so it guards the square your bishop will land on, then drop the bishop in with check: the rook holds it, and the bishop's diagonal X-rays through the king to deny the far flight. It typically arises after a king is dragged out by a sacrifice, especially in sharp lines where one side castles long and strikes down the d-file.
Key ideas
- The bishop delivers the check, not a knight or rook
- A rook on the open file defends the bishop so the king cannot take it
- The bishop's X-ray reaches through the king to seal a far flight (b6)
- The king is smothered by its own pieces, not by yours
- Born from Réti–Tartakower, Vienna 1910, after a queen sacrifice
- Its twin, Rd8#, is the Opera (Morphy) mate, not Réti's
Famous example
Réti–Tartakower, Vienna 1910: 9.Qd8+ Kxd8 10.Bg5+ Kc7 11.Bd8#. The bishop mates on d8, defended by the rook on d1, while Black's king is hemmed in by its own pieces. (After the alternative 10...Ke8 11.Rd8# the rook mates instead – that is the Opera Mate, not Réti's.)