Chess Openings Lab
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King's Gambit Accepted: Bonsch-Osmolovsky Variation

The Bonsch-Osmolovsky Variation is 3.Nf3 Ne7, where Black develops the king's knight to e7 heading for g6 or d5. White builds a center with Nc3 and d4, while Black hits back with ...d5 and uses the knight to defend the f4 pawn or blockade on d5.

Moves
1.e4 e5 2.f4 exf4 3.Nf3 Ne7
ECO
C34
Engine
+0.10 · level (Stockfish 17.1, depth 20)
Played
509 games in our lichess sample
White scores
47.4%

Key ideas for both sides

White

  • Develop with Nc3 and d4, building a strong center before Black can play ...d5.
  • After ...d5 and ...dxe4, recapture with the knight on e4 and check with Bb5+.
  • Try Qe2, so that ...d5 and exd5 leave the e7 knight pinned to the king.
  • Win back the f4 pawn with Bxf4 once Black's knights move away.

Black

  • Play ...d5 to challenge the center, then ...dxe4 and ...Nd5 to blockade.
  • Use ...Ng6 to protect the f4 pawn and keep the extra material.
  • Develop with ...Nc6 and ...Bb4 to pressure the c3 knight and the e4 pawn.
  • Keep the king safe with quick castling once the center opens up.

Plans and pawn structure

After 4.Nc3 d5 5.d4 dxe4 6.Nxe4 Nd5 7.Bb5+ c6 White has a d4 pawn and no e-pawn, while Black has no d-pawn. White plays Bc4, O-O and Bxf4 to regain material and uses the half-open e-file. Black wants ...Be7, ...O-O and to keep the d5 knight centralized. Material and piece play are balanced if White wins f4 back, while Black is happy if the pawn survives.

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 +0.10: level. Its three top choices for White:

  1. +0.10 4.Nc3 d5 5.d4 dxe4 6.Nxe4 Nd5
  2. +0.08 4.d4 d5 5.Nc3 dxe4 6.Nxe4 Nd5
  3. −0.01 4.Qe2 Ng6 5.Nc3 Nc6 6.d4 Bb4

Pawns, from White's side.

How it scores on lichess

509 rated lichess games reached this position; White scored 47.4%.

1200–159957.0%
1600–199949.4%
2000 and up32.9%

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

How to play against it

As White, play 4.Nc3 or 4.d4 and develop quickly. After ...d5, recapture on e4 with the knight and use Bb5+. Avoid slow play that lets Black keep the f4 pawn with ...Ng6. The d4 pawn gives you space, so keep pieces active around it.

Questions

What are the moves of the King's Gambit Accepted: Bonsch-Osmolovsky Variation?

The King's Gambit Accepted: Bonsch-Osmolovsky Variation starts 1.e4 e5 2.f4 exf4 3.Nf3 Ne7. Its ECO code is C34.

Is the King's Gambit Accepted: Bonsch-Osmolovsky Variation good for Black?

Stockfish 17.1 rates the position +0.10 at depth 20, which is level. In 509 lichess games from our sample, White scored 47.4%. A flexible choice for Black that avoids heavy theory; White gets a center and equal chances.

What is the main idea of the King's Gambit Accepted: Bonsch-Osmolovsky Variation?

Black develops ...Ne7 and plans ...d5 or ...Ng6. White builds a center with Nc3 and d4, and the game becomes balanced once White regains the f4 pawn.

What should White play next?

The engine's first choice is Nc3, with d4 and Qe2 close behind. 4.Nc3 develops and prepares d4, keeping the center strong.

Updated October 2026. Sources and method.