The Légal Trap, also known as the Blackburne Trap or Légal Pseudo-Sacrifice and Légal Mate, is a well-known chess opening trap that involves sacrificing the queen and then using minor pieces to checkmate if Black captures the queen. The trap is named after Sire de Légall, a French player, and was frequently used by Joseph Henry Blackburne, a prominent British chess master who was among the top five players in the world during the latter part of the 19th century.
Fun fact: Légal’s outstanding queen sacrifice is actually a blunder, at least in the original version of the trap (see the game Légal vs. Saint Brie below). However, the beauty of the final mating net wasn’t affected by this detail at all.
Another fun fact: Most publications reference a slightly modified version of the Légal Trap without developing the queen-side knight to c6. However, recent research has revealed that the move order of the game may have been adjusted retrospectively in order to correct a flaw in the original game.