Chess Openings Lab
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French Advance Bb5+ trap

In the French Advance, Black wins the d4 pawn with 7...Nxd4 and then the knight with 8...Qxd4. White answers 9.Bb5+, a check that uncovers the queen on d1 against the black queen on d4.

Opening
French Defense: Advance Variation, Milner-Barry Gambit
Moves
1.e4 e6 2.d4 d5 3.e5 c5 4.c3 Nc6 5.Nf3 Qb6 6.Bd3 cxd4 7.cxd4 Nxd4 8.Nxd4 Qxd4 9.Bb5+
Set by
White
The mistake
7...Nxd4
Checked
every move legal; result confirmed by Stockfish 17.1

How the trap works

This trap comes from the French Advance: 1.e4 e6 2.d4 d5 3.e5 c5 4.c3 Nc6 5.Nf3 Qb6. Black piles up on the d4 pawn. White plays 6.Bd3, and after 6...cxd4 7.cxd4 the d4 pawn looks weak. It is attacked by the knight on c6 and the queen on b6. Only the knight on f3 defends it, because the bishop on d3 blocks the white queen's view of the d-file.

  • 7...Nxd4? is the mistake. Two attackers against one defender looks like a free pawn, but the evaluation turns clearly in White's favor.
  • 8.Nxd4 takes the knight. Black's queen is now looking at the d4 knight.
  • 8...Qxd4?? makes it worse. The queen on d4 now stands on the open d-file opposite the queen on d1.
  • 9.Bb5+ is a discovered attack. The bishop leaves d3, which opens the d-file, and it checks the king along b5, c6, d7 and e8 at the same time.

Black must answer the check, and then the white queen takes the black queen on d4. That is why the evaluation jumps again after 8...Qxd4.

The exact moment it goes wrong is 7...Nxd4. Even without 8...Qxd4, Black has given a knight for a pawn. The idea behind the trap is that the bishop on d3 is doing two jobs: it blocks the d-file and it is ready to check on b5.

The cure for Black is ...Bd7. That move covers b5, so the check is no longer possible, and only then is the capture on d4 a real threat. In the French Advance, d4 is Black's main target, but the timing has to be right.

How Black avoids it

Black should play ...Bd7 first. It develops and covers b5, so a later knight capture on d4 does not run into a bishop check on that diagonal.

Questions

How does the French Advance Bb5+ trap work?

After 8.Nxd4 Qxd4, the d-file between the queens is open. 9.Bb5+ checks along the b5-e8 diagonal, Black must deal with the king, and then the white queen takes on d4.

What is the losing move in the French Advance Bb5+ trap?

Black's mistake is 7...Nxd4. Black should play ...Bd7 first. It develops and covers b5, so a later knight capture on d4 does not run into a bishop check on that diagonal.

Is the French Advance Bb5+ trap worth playing for?

Yes for White. 6.Bd3 is a sound setup and the evaluation stays level until Black grabs on d4.

Where it comes from

More opening traps