English Opening: Agincourt Defense, Bogoljubow Defense
ECO A13
Move order
1. c4 e6 2. Nf3 d5 3. g3 Nf6 4. Bg2 Bd6
Ideas
ECO A covers irregular and flank openings—systems that skip the main e4/d4 fight early. White controls d5 without committing the d-pawn—the English family. This entry tracks a longer branch in the opening tree. Use the diagram and SAN list to recognize the tabiya, then try the line against Maia to explore typical plans in practice.