- OpeningRuy Lopez, Berlin Defense
- The mistake5.Nxe5
- The endWins material
The trap
The trap arises in the Berlin Defense of the Ruy Lopez: 1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.d3. Black retreats the knight with 4…Ne7, and the pawn on e5 is suddenly undefended.
1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Ne7 5. Nxe5 c6 6. Ba4 Qa5+ 7. Nc3 Qxe5
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Why it's easy to fall for
The pawn on e5 looks free, and 5.Nxe5 is the first move most players think of. Black's knight move also looks weak, and it feels right to punish it.
But after 5…c6! the bishop on b5 is attacked, and Black threatens …Qa5+, a check that also attacks the knight on e5. If the bishop moves away, to a4 or c4, the fork comes. White can cover a5 with 6.Nc4, but then Black wins material anyway with 6…d6 and 7…b5.
What White should have played
Play 5.Bc4 or another developing move and leave the pawn alone. Black's knight on e7 blocks the bishop on f8, and White is slightly better.
5. Bc4
Right. The bishop goes to c4 and aims at f7, and White is slightly better. Black's knight stands passively on e7.
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How it ends
Black wins a piece for a pawn. After 6.Nc4, by the way, White threatens 7.Nd6, which is a smothered mate, and Black has to deal with that. With 6…d6 7.Ba4 b5 Black still wins a piece, because the pawn forks the bishop and the knight.
How often does it happen?
Our numbers reach as far as 4…Ne7, which 93,044 of the 2,338,266 games between club players in that position played (4%). Black won 53% of those games. After that the position is too rare to be among the positions we have counted, so we can't say how often the mistake itself is made.
Our numbers reach as far as 4…Ne7, which 42,732 of the 709,222 games between strong players in that position played (6%). Black won 52% of those games. After that the position is too rare to be among the positions we have counted, so we can't say how often the mistake itself is made.
Move by move: club players
| Move | Games in the position | Played the move | Then White won | Draw | Black won |
|---|---|---|---|---|---|
| 4.d3 | 9,672,559 | 2,337,083 (24%) | 51% | 5% | 44% |
| 4…Ne7 | 2,338,266 | 93,044 (4%) | 43% | 4% | 53% |
Move by move: strong players
| Move | Games in the position | Played the move | Then White won | Draw | Black won |
|---|---|---|---|---|---|
| 4.d3 | 2,427,326 | 709,076 (29%) | 49% | 6% | 45% |
| 4…Ne7 | 709,222 | 42,732 (6%) | 43% | 5% | 52% |
"Played the move": of the games in the position, how many continued with the move of the trap line; then how those games ended. A position missing from the table is too rare for our numbers. Source: games on Lichess in blitz, rapid and classical, fetched 6 November 2026. Club players means games where the players average 1600 or more, strong players games where they average 2000 or more.
Explore the position on the analysis board: the moves club players choose here and how the games tend to end.
Try it
White has just taken the pawn with 5.Nxe5. Black to move: win a piece!
Your opponent moves…
The history
The trap is named after James Mortimer. He played 4…Ne7 in the great London tournament of 1883, against Berthold Englisch, Samuel Rosenthal and Josef Noa, and lost all three games. The tournament winner, Johannes Zukertort, also played the move against Englisch, and that game was drawn.
In the book Chess Traps, Pitfalls and Swindles (1954), Israel Horowitz and Fred Reinfeld call 4…Ne7 a time-wasting retreat to an inferior square. They also write that the trap was nevertheless in vogue for many years.
Frequently asked questions
What is the Mortimer Trap?
A trap in the Ruy Lopez. Black plays 4…Ne7, and if White takes the pawn on e5, 5…c6! and 6…Qa5+ follow, forking the king and the knight. White loses a piece.
Is 4…Ne7 a good move?
It's playable but a little passive: the knight moves twice. Still, White shouldn't take the pawn on e5. With a quiet developing move White is slightly better.
Every move on this page has been checked against the rules of chess, and every judgement of who stands better has been checked with a chess computer.
Updated November 14, 2026
4… Ne7
The knight retreats and leaves e5 undefended. The move wastes time, but it sets a trap.