Bogo-Indian Defense: Retreat Variation

The Bogo-Indian Defense: Retreat Variation is a chess opening classified under ECO code E11 in the Indian Defences family, where Black responds to 1.d4 with 1...Nf6, including the Nimzo-Indian, Queen's Indian, and King's Indian. It is reached after 6 moves: 1. d4 Nf6 2. c4 e6 3. g3 Bb4+ 4. Bd2 Be7 5. Bg2 d5 6. Nf3 O-O. The resulting position leaves white to move.