Four Knights Game: Spanish Variation, Nimzowitsch Variation

The Four Knights Game: Spanish Variation, Nimzowitsch Variation is a chess opening classified under ECO code C49 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 6 moves: 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5 Bb4 5. O-O O-O 6. Bxc6. The resulting position leaves black to move.