Légal's mate
Also known as Legall's mate, Legal's mate, Blackburne's mate (informal alias)
Légal's mate is the most celebrated queen sacrifice in chess. White lets the queen be captured, then weaves a mating net with a bishop and two knights. It punishes the early ...Bg4 pin on the king's knight when the defender forgets that the pin is only relative and that f7 is desperately weak.
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How it works
Black's bishop on g4 pins the f3-knight to the queen, but the pin is only relative. White plays Nxe5 anyway. If Black grabs the queen with ...Bxd1, White strikes: Bxf7+ forces the king to e7, the only legal square, since the e5-knight covers d7. Then Nd5 is mate. The d5-knight gives check and guards f6; the f7-bishop covers e6 and e8; the e5-knight guards d7; and Black's own pieces and the d6-pawn block the rest. The checking knight cannot be captured or blocked, so the king, a whole queen up, is mated.
How to spot it
It arises in open games (1.e4 e5) when the opponent plays an early ...Bg4 to pin your king's knight while their king still sits on e8 and f7 is guarded only by the king. Look for a bishop already aimed at f7, a knight that can leap into e5, and a third piece (the queen's knight) able to reach d5. The trigger is realising the pin is relative - sacrificing the queen is sound because three minor pieces mate first. Black should simply decline with ...dxe5.
Key ideas
- A pin on a knight in front of the queen is relative, not absolute - you may still move the knight
- Bxf7+ is the classic king-hunt sacrifice, dragging the king off e8
- Three coordinated minor pieces can mate even when a whole queen down
- f7 is the weakest square in the opening, defended only by the king
- Black should decline the queen with ...dxe5 and stay a pawn up
Famous example
Named after the Sire de Légal, mentor of the great Philidor, who reputedly won with it in a Paris cafe around 1750. The same idea recurs endlessly in club and online games, often appearing in casual games of later masters such as Blackburne.