The Accelerated, ...c5 Qb6 is a variation of the London System, catalogued as ECO A48. The line runs 1. d4 d5 2. Bf4 Nf6 3. e3 c5 4. Nf3 Nc6 5. c3 Qb6, reaching the position shown below after 10 half-moves.
Both sides have pawns in the centre (White on d4, Black on d5), and one pawn capture is available, so the structure has not settled yet. Development is level at two minor pieces each. It is White to move after five moves.
On the London System generally: A solid system for White with d4, Nf3, Bf4. Easy to learn with consistent plans.
You can play through this variation move by move in your browser — Learn mode walks the line with an explanation at each step, and Drill mode replays it from memory so you find out whether you actually know it. No account is required.
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The Accelerated, ...c5 Qb6 goes 1. d4 d5 2. Bf4 Nf6 3. e3 c5 4. Nf3 Nc6 5. c3 Qb6. It is a variation of the London System and is catalogued as ECO A48.
The Accelerated, ...c5 Qb6 is ECO A48. ECO codes group openings by their move order, so nearby codes cover closely related lines of the London System.
Stockfish evaluates the position after 1. d4 d5 2. Bf4 Nf6 3. e3 c5 4. Nf3 Nc6 5. c3 Qb6 at -0.01 at depth 18, which is balanced. Engine evaluation is only a starting point — at club level the practical value of a line is mostly about whether you know its plans better than your opponent does.
Both sides have pawns in the centre (White on d4, Black on d5), and one pawn capture is available, so the structure has not settled yet. Development is level at two minor pieces each. It is White to move.