Chess Opening Theory/1. e4/1...e5/2. f4/2...f6

2...f6? is an inferior way to decline the king's gambit.

After 3. fxe5!?, recapturing with the pawn 3...fxe5? is a mistake. Despite appearances, the f-pawn is not able to defend e5 yet due to tactics involving Black's weakened king. 4. Qh5+! g6 5. Qxe5+ Qe7 6. Qxh8 wins a rook. This line is comparable to the Damiano defence, 1. e4 e5 2. Nf3 f6?.

After 3. fxe5, Black's best continuation is 3...Nc6, the Soller-Zilbermints gambit. This adds an attacker to e5: the purpose is that Black now threatens 4...fxe5, as 5. Qh5? g6 and, in this line, the knight defends e5 so White doesn't have the option of Qxe5+.

4. exf6?! allows Black to recapture while developing a piece, 4...Nxf6. Black is ahead in development and has equalised.

If 4. Nf3, a solid developing move, the position of the knight precludes tactics involving Qh5+, so Black may safely recapture 4...fxe5.

4. Bb5 is the critical line. White threatens to trade off the knight and so prevent e5 from being recaptured, e.g. 4...fxe5? 5. Bxc6 dxc6 6. Qh5+ etc. If 4...Nxe5 5. d4 comes with tempo. An example continuation is 5...Ng6 6. h4 c6 7. Bd3 d5 8. h5 dxe4 9. Qe2 Bb4+ 10. c3 N6e7 11. Qxe4⩲.

However, White needn't even take the e-pawn straight away. Many other moves are good for White. Black's f-pawn is left awkwardly placed, so by leaving the tension White denies Black the options of ...Nf6 and ...Qh4+.

White can play 3. Nf3, though unlike in other king's gambit lines, there is no urgency to control h4.

3. Nc3 (controlling d5) Nc6 gives White an improved Max Lange Vienna game. Then, the engine idea is 4. Bc4, with the idea of 5. Bxg8! Rxg8 6. Qh4+.