Chess Opening Theory/1. e4/1...e6/2. d4/2...d5/3. e5/3...c5

Advance variation C02 Advance variation 3...c5 Black's plan is straightforward: they want to eliminate White's pawn chain, and after doing so, will find it easier to develop the pieces of their kingside to good squares. 3...c5 attacks the base of the pawn chain. Although White's d-pawn is already defended once by the queen, if White allows Black to take on d4 their e-pawn becomes loose and hard to defend.e.g. 4. Nc3? cxd4 5. Qxd4 Nc6 (attacks the queen and e5) 6. Qf4 (only move to keep contact with the e5 pawn. 6. Qe3?? d4! forks queen and knight) d4 7. Ne4 Qa5+ 8. Bd2 Qxe5 9. Qxe5 Nxe5. Much better would be for White to retake on d4 with a pawn. Therefore, 4. c3 is the main line. If 4...cxd4 5. cxd4 and White has replaced their d-pawn and Black's position will be just as cramped as it was before. So, if Black hopes to eliminate the pawn on d4 permanently, they must bring more pressure with ...Nc6 and ...Qb6. 4. Nf3, the Nimzowitsch system, supports the centre while developing a piece instead. This allows Black to undermine the pawn chain, as if Black takes on d4 (either next or after ...Nc6) Nxd4 doesn't solve the problem of the loose e5 pawn. However, this is usually played with the idea of not taking back straight away but prioritising development: 4...Nc6 5. Bd3 cxd4 6. O-O, or 4...cxd4 5. Bd3 Nc6 6. O-O. The knight continues to support e5 from f3. 4. Qg4?, the Nimzowitsch attack or gambit, similarly has the idea of sacrificing the d4-pawn in order to gain kingside initiative as a compensation. Taking the pawn, 4. dxc5?, the Steinitz variation, concedes the pawn centre as Black wished. Black recovers the pawn easily enough while developing with ...Bxc5. Perhaps White intends keeping c3 available for the knight and supporting the e5 pawn with f4, a la the classical French also named for Steinitz, 3. Nc3 Nf6 4. e5 which may continue 4...Nfd7 5. f4 c5 6. dxc5 Bxc5.e.g. Steinitz v Vazquez (1888) - Chessgames.com Theory table 4. c3 Nc6 5. Nf3 Bd7 6. Be2 Nge7 7. Na3 cxd4 8. cxd4 Nf5 9. Nc2 Qb6 10. O-O Rc8 Advance variation 4. Nf3 Nc6 5. Bd3 cxd4 6. O-O Nimzowitsch system 4. dxc5? Nc6 5. Nf3 Bxc5 6. Bd3 f6 7. Qe2 fxe5 8. Nxe5 Nxe5 9. Qxe5 Nf6 Steinitz variation - 4. Qg4? cxd4 5. Nf3 Nc6 6. Bd3 Qc7?! 7. Bf4 Nge7 8. O-O Ng6 Nimzowitsch attack - References French Defence See also