Alekhine Defense: Four Pawns Attack

1. e4 Nf6 2. e5 Nd5 3. d4 d6 4. c4 Nb6 5. f4

Alekhine Defense: Four Pawns Attack is catalogued under ECO code B03. It is reached after 5 moves (9 half-moves): 1. e4 Nf6 2. e5 Nd5 3. d4 d6 4. c4 Nb6 5. f4. After the last move it is Black to play. White opens 1. e4. It is a named variation of the Alekhine Defense, which has 56 catalogued lines in total.

Position shown after the last move; Black to play.