Accelerated London System, Steinitz Countergambit Accepted

The Steinitz Countergambit Accepted arises when White captures the c-pawn offered by 2...c5 instead of supporting d4 with e3 or c3. The material gain is only temporary. The capture removes White's d-pawn from the center, leaves Black's d5-pawn unopposed, and gives White doubled c-pawns. Black can regain the pawn with moves such as ...e6 and ...Bxc5 or a queen check on a5. Wikibooks marks 3. dxc5 as dubious, and engines rate the position as level.

3...Nc6 is by far the most common reply. It develops a piece and prepares ...e5, which gains time against the f4-bishop. The classic example is Mason–Steinitz, 1883, in which Mason, the pioneer of the London setup, was outplayed after 3...Nc6 4. Nf3 f6 5. e3 e5 6. Bg3 Bxc5. Black recovered the pawn and set up a broad pawn center. 3...e6 is the second choice and opens the f8-bishop's diagonal for an early recapture on c5. The check 3...Qa5+ is played less often, and White has scored noticeably better against it. Across all lines, Black wins slightly more often than White in online games.