Legal's mate
Legal's mate is an opening trap in which White lets Black capture the queen and then checkmates with a bishop and two knights, punishing a Black player who takes the offered piece.
Also called: Legal trap
The usual move order is 1.e4 e5 2.Nf3 d6 3.Bc4 Bg4 4.Nc3 g6. Black's bishop on g4 pins the knight on f3 to the queen, and Black expects to win a piece. Instead White plays 5.Nxe5, ignoring the pin and leaving the queen on d1 attacked by the bishop.
If Black takes the queen with Bxd1, White plays Bxf7+. The king has only one move, Ke7, and then Nd5 is checkmate. The bishop on f7 and the knights on d5 and e5 together cover every escape square, and the king is hemmed in by its own pieces. Black can also decline the queen, which is safer.
To use it, remember the setup: bishop on c4 aimed at f7, knight on c3 ready to jump to d5, and a knight on e5 that protects the bishop when it lands on f7. To avoid it, before you take a queen that is offered for free, look at every check White has, especially Bxf7+.
In the diagram, which arises after Black's queen was taken on d1 and White checked on f7, White plays Nd5#. The knight on d5 checks the king on e7 and covers f6. The bishop on f7 covers e6 and e8, the knight on e5 covers d7, and Black's own queen, bishop and pawn fill d8, f8 and d6.
Compare it with Fool's mate. Fool's mate is the quickest checkmate possible: Black mates on the second move with Qh4 after White has pushed the f and g pawns, which leaves the king's diagonal wide open.
Compare it with Scholar's mate. Scholar's mate is a four-move checkmate on f7: White's queen and bishop both aim at that square, where only the king defends, and Qxf7 ends the game when Black overlooks it.
Also worth reading is Trap in the opening. A trap in the opening is a move or setup that invites a natural-looking reply, often a grab of material, which then loses to a prepared tactic, so the side that falls for it is worse or lost within a few moves.
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Related terms
Scholar's mate is a four-move checkmate on f7: White's queen and bishop both aim at that square, where only the king defends, and Qxf7 ends the game when Black overlooks it.
Fool's mate is the quickest checkmate possible: Black mates on the second move with Qh4 after White has pushed the f and g pawns, which leaves the king's diagonal wide open.
A trap in the opening is a move or setup that invites a natural-looking reply, often a grab of material, which then loses to a prepared tactic, so the side that falls for it is worse or lost within a few moves.
A queen sacrifice gives up the strongest piece on the board, usually with a check or a capture, to win through a forced checkmate or to gain enough other material to be clearly ahead.
Checkmate, or mate, ends a chess game at once: the king of the side to move is under attack, and none of that side's legal moves can remove the attack, so the player who delivered it wins.
Openings where it occurs
Guides that go further
What to decide first, the questions to ask, what a first lesson should show and the red flags to avoid.
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