London System: Poisoned Pawn Variation

About this variation

Black attacks b2 with an early ...Qb6. White usually offers the pawn with Nc3, or defends it with Qb3 or Qc1.

The Poisoned Pawn Variation of the London arises when Black brings the queen out early with ...Qb6, hitting d4 and the b2 pawn left undefended by the bishop on f4, which is the most direct way to punish White's early bishop development. The Poisoned Pawn Variation is 1. d4 d5 2. Nf3 Nf6 3. Bf4 c5 4. e3 Qb6 5. Nc3. White ignores the attack on b2 and develops, offering the pawn for time.

Grabbing the pawn with 5...Qxb2? is a mistake: 6. Nb5! threatens Nc7+ and Rb1, and White is much better, which gives the line its name. Black usually plays 5...a6, 5...Bd7 or 5...c4 instead. The quieter alternatives for White are 5. Qc1, which defends the pawn and keeps queens on, and 5. Nbd2. In the accelerated move order 1. d4 d5 2. Bf4 c5 3. e3 Nc6 4. c3 Qb6, White usually plays 5. Qb3, offering a queen trade; after 5...Qxb3 6. axb3 White gets the open a-file for the rook as compensation for the doubled pawns.

The resulting middlegames are usually closed or semi-closed. White keeps the solid pawn chain on c3, d4 and e3, and Black often follows with ...Nf6, ...e6, ...Bd6 to challenge the bishop on f4, and ...O-O. White's main plans are Ne5 and a kingside attack, or, after the queen trade, play down the a-file. Black's are pressure on d4 and the queenside, and ...e5 to free the position.

The Poisoned Pawn is a good choice for Black players who want to fight the London on concrete grounds rather than through slow maneuvering. London players should know the line well, as it is the most common attempt to disrupt their set-up.

Studying a few model games from both sides is the fastest way to learn the line. Pay attention to how White uses the half-open a-file after the queen trade, and how Black uses the c-file and the pressure on d4 when queens stay on the board.

It is one of the main lines of the London System.