The Legal Trap or Blackburne Trap (also known as Legal Mate) is a

chess opening The opening is the initial stage of a chess game. It usually consists of established Chess_theory#Opening_theory, theory. The other phases are the chess middlegame, middlegame and the chess endgame, endgame. Many opening sequences, known as ''op ...

, characterized by a

queen sacrifice In chess, a queen sacrifice is a move that sacrifices a queen, the most powerful piece, in return for some compensation, such as a tactical or positional advantage. Queen sacrifice: real versus sham In his book ''The Art of Sacrifice in Ches ...

followed by checkmate involving three minor pieces if Black accepts the sacrifice. The trap is named after the French player Sire de Légall.

Joseph Henry Blackburne Joseph Henry Blackburne (10 December 1841 – 1 September 1924) was a British chess player. Nicknamed "The Black Death", he dominated the British scene during the latter part of the 19th century. Blackburne learned the game at the relatively late ...

, a British master and one of the world's top five players in the latter part of the 19th century, set the trap on many occasions.

Natural move sequence

There are a number of ways the trap can arise; the one below shows a natural move sequence from a

simultaneous exhibition A simultaneous exhibition or simultaneous display is a board game exhibition (commonly chess or Go) in which one player (typically of high rank, such as a grandmaster or dan-level player) plays multiple games at a time with a number of other pl ...

in Paris. André Cheron, one of France's leading players, won with the trap as White against Jeanlose: 1. e4 e5 2. Nf3 Nc6 3. Bc4 d6 :The Semi-Italian Opening. 4. Nc3 Bg4 :Black

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s the

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in the fight over the center. Strategically this is a sound idea, but there is a tactical flaw with the move. 5. h3 :In this position 5.Nxe5 would be . While the white queen still cannot be taken (5...Bxd1) without succumbing to a checkmate in two moves, 5...Nxe5 would win the white knight (for the pawn) and protect the bishop on g4. Instead, with 5.h3, White "puts the question" to the

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which must either retreat on the c8–h3 diagonal, capture the knight, be captured, or as in this game, move to an insecure square. 5... Bh5 (diagram) :Black apparently maintains the pin, but this is a tactical mistake which loses at least a

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(see below). Relatively best is 5...Bxf3 (or 5...Bd7), surrendering the and giving White a comfortable lead in , but maintaining equality. 5...Be6 is also possible. 6. Nxe5 :The tactical refutation. White seemingly ignores the pin and surrenders the

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. Black's best course now is to play 6...Nxe5, where with 7.Qxh5 Nxc4 8.Qb5+ followed by 9.Qxc4, White remains a pawn ahead, but Black can at least play on. Instead, if Black takes the queen, White has checkmate in two moves: 6... Bxd1 : A blunder, winning the queen but losing the game. Black should have played 6...Nxe5 or 6...dxe5 as mentioned in the previous note. 7. Bxf7+ Ke7 8. Nd5 :The final position is a pure mate, meaning that for each of the eight squares around the black king, there is exactly one reason the king cannot move there, and exactly one reason why the king cannot remain on its current square.

Légal versus Saint Brie

The original game featured Légal playing at rook odds (without Ra1) against Saint Brie in

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1750: 1. e4 e5 2. Nf3 d6 3. Bc4 Bg4?! 4. Nc3 g6? 5. Nxe5 Bxd1?? 6. Bxf7+ Ke7 7. Nd5# :The above version is cited in most publications, sometimes with the move 4... h6 instead of 4... g6. However, research suggests that the of the game had been altered retrospectively in order to remove a flaw in the original game. Also the year 1750 is assumed to be wrong; it is more likely that the game was played in 1787, and that the original move order was: 1. e4 e5 2. Bc4 d6 3. Nf3 Nc6 4. Nc3 Bg4 5. Nxe5? Bxd1?? 6. Bxf7+ Ke7 7. Nd5# 1–0 :Here the combination is flawed, as with 5... Nxe5 Black could have gained a piece. It is reported that Légal disguised his trap with a psychological trick: he first touched the knight on f3 and then retreated his hand as if realizing only now that the knight was pinned. Then, after his opponent reminded him of the

touch-move rule The touch-move rule in chess specifies that a player, having the move, who deliberately touches a piece on the board must move or capture that piece if it is legal to do so. If it is the player's piece that was touched, it must be moved if the p ...

, he played Nxe5, and the opponent grabbed the queen without thinking twice.

Other variations

Considerations

A mating pattern where a pinned knight moves, allowing the capture of the player's queen but leading to a checkmate with three minor pieces, occasionally occurs at lower levels of play, though masters would not normally fall for it. According to Bjerke (''Spillet i mitt liv''), the Légal Trap has ensnared countless unwary players. One author writes that "Blackburne sprang it several hundreds of times during his annual tours."Francis J. Wellmuth ''The Golden Treasury of Chess''; Chess Review 1943, p. 147.

References

Bibliography *

External links