Philidor Defense: Philidor Countergambit, Zukertort Variation

The Philidor Defense: Philidor Countergambit, Zukertort Variation is a chess opening classified under ECO code C41 in the Open Games & French Defense family, beginning with 1.e4 e5 or 1.e4 e6, including the Italian Game, Ruy Lopez, and French Defense. It is reached after 4 moves: 1. e4 e5 2. Nf3 d6 3. d4 f5 4. Nc3. The resulting position leaves black to move.