Bogo-Indian Defense

The Bogo-Indian Defense (Bogo-Indian Defense in British spelling) arises when Black meets 1. d4 Nf6 2. c4 e6 3. Nf3 with 3...Bb4+. White's third move sidesteps the Nimzo-Indian, but Black develops the king's bishop to b4 anyway, now with check. Unlike 3...b6 (the Queen's Indian) or 3...d5 (the Queen's Gambit Declined), the check asks White to commit a piece to the block at once. The opening is about half as common as the Queen's Indian and can also be reached through the Keres Defense, 1. d4 e6 2. c4 Bb4+. It is named after Efim Bogoljubow, who is credited with introducing it and played it often in the 1920s.

White has three main replies. 4. Nc3 transposes into the Nimzo-Indian, so the independent lines are 4. Bd2, by far the most common, and 4. Nbd2, the Grünfeld Variation. The knight block aims to gain the bishop pair or force the bishop back, at the cost of putting the knight on a less active square where it obstructs the c1-bishop; Black most often continues 4...b6, 4...O-O or 4...d5. The New England Variation, 4. Nfd2, is a rarity.

After 4. Bd2 the bishop is attacked. The most frequent answer is the Nimzowitsch Variation, 4...Qe7, which keeps the tension and supports a dark-square setup with ...d6 and ...e5. A main line runs 5. g3 Nc6 6. Nc3 Bxc3 7. Bxc3 Ne4, while 6. Bg2 Bxd2+ 7. Nbxd2 d6 8. O-O a5 9. e4 e5 produces a closed center; both are assessed as equal. The Exchange Variation, 4...Bxd2+, is the simplest route and was used by Ulf Andersson, often to secure a draw. The Wade-Smyslov Variation, 4...a5, which David Bronstein tried, gains queenside space while conceding some structural weaknesses. In the Vitolins Variation, 4...c5 5. Bxb4 cxb4, Black accepts doubled pawns drawn away from the center, though the b4-pawn denies White's knight the c3-square, and 6. a3 is a common way to remove it. The Retreat Variation, 4...Be7, is passive but solid, the lost tempo offset by the bishop's modest post on d2. 4...Nc6 is the Haiti Variation.

Exchanges are frequent and the positions tend toward equality, with a strong drawing tendency in master play. The engine gives White a slight edge, and in online games White scores somewhat better than Black. Players who have adopted the opening include Nimzowitsch, Keres, Petrosian, Larsen, Smyslov, Korchnoi, Andersson, Michael Adams and Nikita Vitiugov. The Monticelli Trap, a tactical motif reached via a Queen's Indian move order with an early ...Bb4+, is also classified under this name.