White is pinned, White ignores it, White loses the queen and mates on move seven. The whole thing is 1.e4 e5 2.Nf3 d6 3.Bc4 Bg4 4.Nc3 g6 5.Nxe5 Bxd1 6.Bxf7+ Ke7 7.Nd5 mate.
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e f g h 1 And the finish, with the black bishop still sitting on d1 holding a queen it will never get to use.
8 7 2 a c d e h 1 The trap carries the name of the Sire de Légal, who played it in Paris around 1750, and it has been catching people ever since.
The pin that is not a pin
After 3…Bg4 the bishop pins the knight on f3 to the white queen on d1. Every beginner is taught that a pinned piece cannot move, and that is the misunderstanding the trap feeds on. A piece pinned against the king cannot legally move. A piece pinned against the queen can move whenever the arithmetic works out, and here it works out beautifully.
5.Nxe5 hangs the queen on purpose. Black’s honest reply is 5…dxe5, when 6.Qxg4 leaves White a pawn up with a healthy position, which is why the sacrifice costs nothing to try.
5…Bxd1 is the human move. A free queen is a free queen. But look at what has left the board on Black’s side of it: nothing. Black’s bishop has wandered to d1 where it does no work at all, the knight on e5 is sitting in the middle of Black’s position, and f7 is defended by one lonely king.
Why the mate works
6.Bxf7+ is check, and the king has exactly one square. Kxf7 is illegal because the knight on e5 defends the bishop, and Kd7 is illegal for the same knight’s sake. So 6…Ke7 is forced, and the black king is standing in the open with his own queen on d8, his own bishop on f8 and his own pawn on d6 taking away three of his squares.
7.Nd5 is mate. The knight checks from d5, and every escape is covered or occupied: d7 by the knight on e5, e6 and e8 by the bishop on f7, f6 by both knights, and the rest by Black’s own pieces. Three minor pieces and not a queen in sight, which is the same idea as the smothered mate: a king suffocated by his own army.
What to take from it
Two habits. Before you pin a knight to a queen, ask what happens if the knight moves anyway, and count the checks that follow. And when someone offers you a queen in the opening, spend thirty seconds looking at their minor pieces rather than at your own material count.
The general skill here is reading a sacrifice as a sequence rather than a loss, and once that clicks, traps like Scholar’s mate start to look like what they are: arithmetic on one square.