411 REFERENCE · Wikibooks
Chess Opening Theory/1. e4/1...e5/2. Nf3/2...d6/3. d4/3...Nd7/4. Bc4/4...Ngf6/5. dxe5/5...dxe5
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Hanham variation C41 Philidor defence → Hanham variation → 5. dxe5
5...dxe5??
This seems to recover the pawn but loses tactically because the pressure White exerts on f7.
6. Ng5! launches a winning attack. White threatens Bxf7+ Ke7 Ne6 trapping Black's queen.
6...Nb6 is the best attempt at defence. 7. Bxf7+ Ke7 8. Qxd8+ Kxd8+++ White is up a pawn in an endgame. Bb3 and Nf7+ forking the king, rook and pawn is threatened.
6...Bb4+ at least allows Black to castle if they give up the bishop. 7. c3 O-O 8. cxb4.
Theory table
+Ng5! +-
Reference
See also