Queen's Gambit Declined: Harrwitz Attack, Two Knights Defense, Blockade Line

1.d4 Nf6 2.c4 e6 3.Nc3 d5 4.Nf3 Be7 5.Bf4 O-O 6.e3 Nbd7 7.c5

ECO D37

The Queen's Gambit Declined: Harrwitz Attack, Two Knights Defense, Blockade Line is a chess opening line in the Queen's Gambit Declined complex, reached after 1.d4 Nf6 2.c4 e6 3.Nc3 d5 4.Nf3 Be7 5.Bf4 O-O 6.e3 Nbd7 7.c5.

It is catalogued under code D37 in the Encyclopaedia of Chess Openings (ECO).

The defining move c5 is chosen by White on move 7.

Study this line with a grandmaster

This position is covered in the Opening Tricks Hall of Fame course: a GM-authored repertoire you study move by move, then practice against a human-like AI opponent.

Every chess term used here is defined in the chess terms glossary. Browse all opening courses or the full ECO code index.