Miles Defense

The Miles Defense arises from the Queen's Knight Defense after 1. e4 e5 2. f4 Nc6 3. Nf3. With the knight now covering h4, fxe5 has become a genuine threat. Black does not defend e5 or open the center with 3...d5. Instead, 3...f5 mirrors White's second move, attacking the e4-pawn and offering a pawn exchange of its own. The line is named after Tony Miles, who advocated it, and it is also known as the Adelaide Countergambit. The position is nearly symmetrical, with both sides' e- and f-pawns in contact. The advance also loosens Black's kingside in the same way that 2. f4 loosened White's.

White most often releases the tension with 4. exf5, which is also the engine's first choice. The main alternatives are 4. Bc4, which develops toward the a2–g8 diagonal, and the quieter 4. d3, which supports e4. Engines give White a slight edge, yet Black has scored well in online play. Stronger players tend to prefer this line to 3...d5, where 4. exd5 Qxd5 5. Nc3 gains White time against the queen.