The Marshall Trap is named after Frank Marshall, the American champion who built his career on exactly this kind of ambush. It lives in the classical Petrov, where Black plants a knight on e4 and backs it up with ...d5, ...Bg4 and ...f5. One natural rook move by White, 10.Re1?, and a five-move combination strips the kingside and wins material by force.
In the main-line Petrov, White attacks the e4 knight with 10.Re1? instead of the correct 10.Nc3. Black answers 10...Bxh2+!, and after 11.Kxh2 Nxf2 the knight forks queen and bishop. The forced sequence ends with 14...Qh4+ and 15...Qxe1+, leaving Black a rook and a pawn up for a bishop.
After 1.e4 e5 2.Nf3 Nf6 3.Nxe5 d6 4.Nf3 Nxe4 5.d4 d5 6.Bd3 Bd6 7.O-O O-O 8.c4 Bg4 9.cxd5 f5, Black's setup looks loose, but every piece points at White's king. 10.Re1? attacks the e4 knight and seems to win it, since d5 has fallen. It loses: 10...Bxh2+! rips the cover off. After 11.Kxh2 Nxf2, the knight forks the d1 queen and the d3 bishop. White saves the queen with 12.Qe2, but 12...Nxd3 13.Qxd3 Bxf3 removes the knight that guarded h4. Now 14.Qxf3 Qh4+ forces 15.Kg1 (g3 is covered by the queen), and 15...Qxe1+ collects the rook that started it all. Count it up: Black gave a bishop and got a rook plus two kingside pawns while White's king sits in the draft.
10. Re1 — 10.Re1? (ply 19) is the losing move. Putting the rook on the e-file against the e4 knight is the most natural move on the board, which is what makes the trap so poisonous. The correct move is 10.Nc3, developing and challenging e4 before Black's attack assembles.
As White, the signal is Black's pawn on f5 supporting a knight on e4 with the bishop pair aimed at your king: that is an attacking formation, not loose pawns. Meet it with 10.Nc3, hitting e4 with a piece while the back rank stays solid. And if you are ever hit by ...Bxh2+ here, know the details: 11.Nxh2 is no escape because 11...Bxd1 simply takes the queen, so the bishop cannot be declined either.
The forced line costs Black a bishop and wins a rook and two pawns (h2 and f2), while trading the rest down. That is the exchange and a pawn, plus the safer king, which the Oxford Companion sums up as a winning material advantage for Black.
No. After 10...Bxh2+ 11.Nxh2 Black plays 11...Bxd1, and the g4 bishop takes the queen because the f3 knight, its only real guard, just left. Both captures lose; White's game was already beyond saving after 10.Re1.
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.