The Mortimer Trap is a piece of pure provocation in the Berlin Ruy Lopez: Black plays the odd-looking 4…Ne7, apparently abandoning the e5-pawn, and dares White to take it. If White grabs the 'free' pawn with 5.Nxe5??, a small combination wins a whole piece. It is named after the 19th-century English player James Mortimer, and it is a textbook lesson in not trusting a pawn that looks too easy.
Black plays 4…Ne7?! to bait White into 5.Nxe5??, then 5…c6! attacks the b5-bishop and, once it moves, …Qa5+ forks the king and the loose e5-knight — winning a piece by force.
After 4…Ne7?! the knight steps off c6, so the e5-pawn looks free for the taking. The greedy 5.Nxe5?? (ply 9) snatches it, but now 5…c6! is the sting: the pawn attacks the bishop on b5 and the bishop must move. Wherever it goes (5…c6 6.Bc4, 6.Ba4 or 6.Be2), Black follows with …Qa5+, a check that simultaneously forks the white king and the undefended knight stranded on e5. White must answer the check, and then …Qxe5 collects the knight — a clean extra piece. The drill ends on 5…c6, the move that sets the fork in motion and wins material by force.
5. Nxe5 — 5.Nxe5?? (ply 9) is the blunder — White accepts the bait and wins a pawn, not seeing that 5…c6 and …Qa5+ will fork the king and the e5-knight. The safe alternatives are to just develop: 5.Nc3 or 5.O-O keep White comfortably better, since 4…Ne7 was a passive, awkward move that Black has to justify.
Don't take the pawn — that is the whole trap. After 4…Ne7?! the e5-pawn only looks loose; capturing it with 5.Nxe5 walks straight into …c6 and the …Qa5+ fork. Instead White should continue developing with 5.Nc3, 5.O-O or 5.c3, keeping a small, safe edge against Black's clumsy knight retreat.
5…c6 forces the b5-bishop to move (say 6.Ba4). Then 6…Qa5+ checks the white king and attacks the knight stranded on e5 at the same time. White must deal with the check, and …Qxe5 wins the knight — a full extra piece.
Not really — it is provocative and a bit passive, and if White simply declines the bait with 5.Nc3 or 5.O-O, Black has just played an awkward knight retreat for nothing. The Mortimer Trap is a swindle that only pays off if White gets greedy.
A trap only works if your opponent makes the mistake — strong players sidestep these, which is why each page also shows how to avoid it. Every line here is checked legal with the same engine the board runs, and every checkmate is verified.