A tricky checkmating theme originating from a chess game played between Legall and St. Brie in 1750. The play went as follows:

1. e4 e5
2. Bc4 d6
3. Nf3 Bg4
4. Nc3 g6
5. Nxe5 Bxd1  Accepting the queen sacrifice seals black's fate; checkmate is now forced.
6. Bxf7+ Ke7
7. Nd5#

Although this looks like a silly trap, it remains more than a curiosity; the tactical idea invented by Legall is an important one which reappears even in modern tournament games. For this reason, an alternative name is Legall's Legacy.