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

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

ECO D37

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

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

The defining move Nbd7 is chosen by Black on move 6.

One named continuation branches from this position: the Blockade Line.

Named variations

• Queen's Gambit Declined: Harrwitz Attack, Two Knights Defense, Blockade Line — ECO D37

Study this line with a grandmaster

This position is covered in the Catalan Opening 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.