King's Gambit Declined

Rather than taking the f4-pawn, Black uses the second move to develop or strike back in the center. These replies share one tactical point. Although 2. f4 attacks e5, it does not yet threaten to win it, because fxe5 would open the e1–h4 diagonal and allow ...Qh4+. Black therefore has a free tempo and no need to defend e5 at once. The same logic warns against haste: 2...Qh4+ is met by 3. g3, and the queen must retreat, as in Keene's Defense with 3...Qe7.

The Classical Variation, 2...Bc5, places the bishop on the a7–g1 diagonal and sets an immediate trap. After 3. fxe5?? Qh4+ 4. g3 Qxe4+, the rook on h1 falls. The normal 3. Nf3 covers h4, so the capture on e5 becomes a genuine threat, and Black usually answers 3...d6. White then often prepares c3 and d4 to build a broad pawn center, while the Soldatenkov Variation takes on e5 at once with 4. fxe5. The line yields balanced positions without the turbulence of the accepted gambit, though it challenges White's setup less directly.

The Falkbeer Countergambit, 2...d5, is the principal modern way to decline. In the main line, 3. exd5 exf4 4. Nf3 Nf6, Black does capture on f4 after all. The aim, however, is to trade the material for rapid development and open lines against White's loosened kingside, not to keep the pawn. This position can also arise from the Modern Defense of the accepted gambit, 2...exf4 3. Nf3 d5.

The Queen's Knight Defense, 2...Nc6, is the reply amateurs choose most often. After 3. Nf3 d5 4. exd5 Qxd5 5. Nc3, White gains time on the queen and keeps a small edge. Stronger players therefore prefer the Miles Defense, 3...f5, which hits back at e4.

The remaining moves are fringe choices. 2...Nf6, Petrov's Defense, was proposed by Petroff and resembles a Latvian Gambit with colors reversed. 2...Qf6, the Norwalde Variation, is playable but makes little use of the time Black has gained. The Panteldakis Countergambit, 2...f5, weakens Black's own king, and 3. exf5 exf4? 4. Qh5+ shows the danger. The Mafia Defense reaches the declined structure through 1. e4 c5 2. f4 e5. Historically, the strength of 2...d5 and 2...Bc5 counted among the reasons Tarrasch dismissed the gambit in the 1930s.