St. George Defense

The St. George Defense answers the Zukertort Opening with 1...a6, the same edge-pawn move that defines the St. George Defense against 1. e4. The move prepares queenside expansion with ...b5 and a possible ...Bb7, but it does nothing to contest the center. Black's main replies to 1. Nf3, 1...d5 and 1...Nf6, both stop 2. e4. After 1...a6, by contrast, White is free to choose any central setup, and Wikibooks marks the move as dubious. The engine gives White a slight edge, and in online play White scores somewhat better than Black.

The engine's preferred replies are 2. e4, 2. g3 and 2. d4. In practice 2. g3 is the most common choice. It heads for a King's Indian Attack or a fianchetto structure in which ...a6 matters little. 2. d4 is almost as popular and claims the center with a queen's pawn setup. The more direct 2. e4, which the engine rates highest, is less common. It takes both central squares at once and leaves Black to justify the lost tempo, much as in the 1. e4 version of the defense. Theory is minimal in all of these lines, and the opening serves mainly as a surprise or a way to steer clear of mainstream structures.