Queen's Gambit Declined: Harrwitz Attack, Two Knights Defense, Blockade Line
ECO D37
Move order
1. d4 Nf6 2. c4 e6 3. Nc3 d5 4. Nf3 Be7 5. Bf4 O-O 6. e3 Nbd7 7. c5
Ideas
ECO D covers queen-pawn games and closed structures, including many Gambits and the Queen's Gambit complex. White builds a pawn center and keeps the position more closed than after 1. e4. 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.