Semi-Slav Defense: Marshall Gambit, Forgotten Variation

The Semi-Slav Defense: Marshall Gambit, Forgotten Variation is a chess opening classified under ECO code D31 in the Closed & Semi-Closed Games family, arising from 1.d4 d5, including the Queen's Gambit, Slav Defense, and related systems. It is reached after 6 moves: 1. d4 d5 2. c4 e6 3. Nc3 c6 4. e4 dxe4 5. Nxe4 Bb4+ 6. Nc3. The resulting position leaves black to move.