Opening Traps/know them from both sides/D00/You play Black

London: the Poisoned b2-Pawn

The London leaves b2 hanging on purpose. Take it before ...e6 and a knight forks king and rook on c7.

Coachedanswers the move you actually played

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Stockfish+0.36

Move 0 of 16 · Black up

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The poisoned b2-pawnFoundation8 moves Sidestepping it: 4...e6as BlackFoundationThe same position from the other chair. Guard d5 before the queen goes anywhere, cover c7 when the knight heads there by another road, and the London's trap is just a normal game.8 moves Deep dive: collecting the rookStructure12 moves

1.2.3.4.5.6.7.8.

StartBefore the first move

The starting position. White moves first, and that single tempo is the whole reason opening theory exists.

The moves in the text are buttons. Press one and the board beside it shows the position.

The idea in one paragraph

Once the London bishop leaves c1, nothing guards b2, and every ...c5 and ...Qb6 aims at it. The trap is in the timing: before ...e6, the queen that goes to b6 leaves d5 with no defender at all, so offers b2 and hits d5 in the same move. Take the pawn and Nxd5 lands one hop from c7, where the knight forks king and rook under the f4-bishop's guard. Play first and the trap is gone. still eyes c7, but covers it.

The pawn structure

There is no pawn structure to learn here; there are two squares. d5 is the one the black queen stops guarding when she goes to b6, and c7 is the one the f4-bishop already guards before the knight ever gets there. Every move in both lines is about who controls those two squares.

The plans

♔ White’s plans

Against an early ...c5 and ...Qb6, answer with while Black's d5-pawn has no defender: b2 is bait, d5 is the target, c7 is where the knight forks.
After , take back on d4 with the queen and let Black trade queens. The check on c7 comes first, the recapture on d4 second.
Against , keep the knight's eye on c7 with : Black has to cover c7 with , and White keeps the engine's small edge with a4, Nf3 and c3.
Once you have played c3, the knight can no longer go to c3 and the trick is unavailable. The London chapter covers the other answers to ...Qb6.

♚ Black’s plans

Play ...e6 before ...Qxb2 is ever on the board: once d5 has a pawn guard, Nxd5 is not a move and the fork never arrives.
Against , put a guard on c7 at once with . The knight looks offside, but it is doing the only job that matters.
Then develop normally (...Nf6, ...Be7, ...O-O) and trade off the b5-knight with ...Bd7 when it suits you.

Traps and things that lose games

The poisoned b2-pawn

and the a8-rook is lost. The cure: .

Its cousin with colours reversed

the Englund Gambit Trap, where it is Black's queen that takes b2 and White who has to know the one safe reply.

And the London's other trap, set against the London player

and the bishop is hunted down (see the ...h5 bishop hunt course).

London players first, because this is the trick that explains why the system can leave b2 unguarded. And everyone who meets the London as Black, because 3...Qb6 is the first idea most players reach for against it.

Your learning path: London: the Poisoned b2-Pawn

Beginner → Intermediate

One trap, two chairs: spring it as the London player, and never pay for it as Black.

FoundationOne sitting
Goal. Know when 4.Nc3 works, and what 4...e6 does to it.
- The timing: the trap exists only while d5 has no pawn guard and the knight can still reach c3.
- The move order of the punishment: Nxd5, Qxd4, and the check on c7 before the recapture on d4.
- From Black's chair: 4...e6, and 5...Na6 against 5.Nb5.
DrillDrill the trap as White until the in-between check on c7 is automatic, then drill the sidestep as Black. Finish with the deep dive once.
Common mistakeRecapturing on d4 with the pawn after 6...Qxd4. Check first: 7.Nc7+ comes before exd4, or the fork never happens.
Move on whenYou can say, without a board, why 4.Nc3 works against 3...Qb6 and does nothing against 3...e6 and 4...Qb6.
StructureAfter the London chapter
Goal. Fold the trap into your London repertoire.
- Why c3 kills the trick: the knight's road to c3 is gone.
- The deep dive: Black's best try 8...e5, and why White takes the rook before the bishop's guard on c7 disappears.
DrillPlay the London against an engine and, every time ...Qb6 appears, stop and ask whether c3 has been played and whether d5 is guarded.
Common mistakePlaying 4.Nc3 after c3 or after ...e6, as a reflex. The trap is a question about two squares; ask it every time.
Move on whenYou spring it when it is there and play the normal London move when it is not.

Whose games to study

The London chapter on this site covers the rest of the ...c5 and ...Qb6 systems. Every evaluation here comes from Stockfish at depth twenty.

What to learn after this

The London System course, and its other trap: the ...h5 bishop hunt, which is set against the London player.