411 REFERENCE · Wikibooks
Chess Opening Theory/1. d4/1...d5/2. c4/2...e6/3. Nc3/3...c6/4. e4/4...dxe4/5. Nxe4/5...Bb4/6. Bd2/6...Qxd4/7. Bxb4
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Semi-Slav defence: Marshall gambit Marshall gambit
7. Bxb4
White takes Black's dark-squared bishop. White's dark-squared bishop is now placed on a very active diagonal, cutting through d6, e7 and f8. Black should play 7...Qxe4+ to not be down a piece.
Theory table
7. ... Qxe4+ 8. Be2 unclear 7. ... ... 8. Ne2 unclear
See also
Semi-Slav Defense Marshall_Gambit