Blackmar-Diemer Gambit Accepted: Ziegler Defense

Key ideas for both sides

White

6.h3 prevents ...Bg4, so the c8 bishop must choose f5, where Bd3 offers a trade.
After the trade on d3, the queen sits on d3 and Bg5 pressures f6, as in the main engine line.
Castle short and use the f-file. Ne5 and a rook on f1 make f7 the target.
6.a3 is a slower idea that rules out ...Bb4 before Black's dark-squared bishop is ready.

Black

Use the new diagonal: ...Qb6 hits d4 and b2 at once, and ...Qa5 can pin the c3 knight.
Develop the c8 bishop before ...e6: ...Bf5 against 6.h3, or ...Bg4 after 6.Bd3.
...g6 and ...Bg7 with short castling is a sturdy plan, as in the third engine line.
...Nbd7 supports ...e5 or ...c5 later, the breaks that strike at White's lone d4 pawn.

Plans and pawn structure

Black's c6 pawn guards d5 and b5, so White's pieces get fewer outposts in the center. White wants Bd3, short castling, Qe2 or Qd3, and Bg5, then pressure on f6 and down the f-file. Black finishes with ...Nbd7, ...e6 or ...g6, and castles. The key break is ...c5 or ...e5 against d4. Once d4 falls or is traded, Black's extra pawn becomes the main story.

Where the engine's main line heads: White pawn d4, no e-pawns for White, no d-pawn for Black. White has a pawn on d4 and no e-pawn; Black has no d-pawn. White has more central space; Black's pieces are free and the d4 pawn is a target.

What the engine plays from here

Stockfish 17.1 at depth 20 rates the position −0.73: a slight edge for Black. Its three top choices for White:

−0.73 6.h3 Bf5 7.Bd3 Bxd3 8.Qxd3 Nbd7
−0.75 6.Bd3 Bg4 7.Be3 e6 8.Qe2 Bb4
−0.77 6.a3 g6 7.Bd3 Bg7 8.h3 O-O

Pawns, from White's side.

How it scores on lichess

477 rated lichess games reached this position; White scored 54.3%.

1200–159964.7%

1600–199950.9%

2000 and up52.1%

Light: White wins. Grey: draws. Dark: Black wins. About the sample.

How to play against it

Take away g4 with 6.h3 and meet ...Bf5 with Bd3 to trade off Black's best minor piece. Keep b2 and d4 protected against an early ...Qb6, for example with Be3 or Qd2. Do not drift: Black's setup is solid, and slow play just leaves you a pawn down with nothing to show.

Questions

What are the moves of the Blackmar-Diemer Gambit Accepted: Ziegler Defense?

The Blackmar-Diemer Gambit Accepted: Ziegler Defense starts 1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 exf3 5.Nxf3 c6. Its ECO code is D00.

Is the Blackmar-Diemer Gambit Accepted: Ziegler Defense good for Black?

Stockfish 17.1 rates the position −0.73 at depth 20, which is a slight edge for Black. In 477 lichess games from our sample, White scored 54.3%. A sensible pick for Black players who like calm, solid structures; White must keep the initiative alive with active pieces.

What is the main idea of the Blackmar-Diemer Gambit Accepted: Ziegler Defense?

Black keeps the extra pawn with a Caro-Kann style setup. The pawn on c6 gives the queen b6 and a5 and keeps White's pieces off d5 and b5, while the c8 bishop still develops outside the pawn chain.

What should White play next?

The engine's first choice is h3, with Bd3 and a3 close behind. 6.h3 stops ...Bg4, so Black's bishop goes to f5 and White can offer to trade it with Bd3.

Updated October 2026. Sources and method.