Key ideas
- The Classical Variation, 2...Bc5, puts the bishop on the a7-g1 diagonal so White cannot castle short. The main line runs 3.Nf3 d6 4.c3, with White preparing d4 to drive the bishop away.
- In the Falkbeer Countergambit, 2...d5 3.exd5, Black can play the old 3...e4, a wedge that cramps White's development, or 3...exf4, which leads to King's Gambit Accepted positions. White's standard answer to 3...e4 is 4.d3, the Charousek Gambit, which breaks up the wedge.
- Other declines include 2...Nf6, 2...Nc6 and Keene's Defense, 2...Qh4+ 3.g3 Qe7, which uses the check to provoke g3 before retreating.
- In the Classical lines, Black usually meets fxe5 with ...dxe5 and fights for the centre with ...Nf6, ...Nc6 and the pin ...Bg4. The game turns on whether White can achieve d4.
Plans for White
Against 2...Bc5, develop with Nf3 and c3, then play d4 to blunt the bishop and make castling possible. Against the Falkbeer, undermine the e4 wedge with d3 rather than clinging to the extra pawn.
Plans for Black
In the Classical, keep the bishop on the a7-g1 diagonal for as long as possible and develop with ...d6, ...Nf6 and ...Nc6. In the Falkbeer, use the lead in development that the pawn bought you.
Watch out
2...Bc5 3.fxe5?? loses to 3...Qh4+. After 4.g3 Qxe4+ the queen forks the king and the rook on h1, and after 4.Ke2 Qxe4 is mate.