Chess Opening Theory/1. d4/1...d5/2. Bf4/2...c5

Black challenges the centre with c5, the Steinitz countergambit,^[1] offering White their c-pawn.

As the pawn is already defended by the Queen, White does not actually need to defend it further: if 3. Nc3 cxd4 4. Qxd4 and White is threatening to win Black's d-pawn: 4...Nc6? 5. Qxd5 Qxd5 6. Nxd5± (if 4...e6 5. Bxb8! Rxb8 and White's centralised queen is unassailable).

Usually however White does end up over-defending the d-pawn, because most of the moves they'd like to play next happen to do so anyway. White usually plays 3. e3, which defends d4 but is also essential for opening up White's kings-side bishop. Other London system-moves 3. c3 or 3. Nf3 may be played and usually transpose.

Accepting the gambit, 3. dxc5?!, is unwise. By taking the pawn, White reduces their control over the centre and Black can easily recover the pawn. Mason, pioneer of the London system, fell into this in his game against Steinitz in 1883.^[2] It continued like this: 3. dxc5?! Nc6 4. Nf3 f6 5. e3 e5 6. Bg3 Bxc5 (see diagram).

A rare sideline here is the Morris countergambit^[3], 3. e4. White gives up their e-pawn in order to push d5 and cramp Black's position. This resembles an Albin Countergambit with colours reversed.

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