Chess Openings Lab
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Sicilian Defense: Portsmouth Gambit

The Portsmouth Gambit is 3.b4, where White offers the b-pawn after 2...Nc6 to deflect the c5 pawn or the knight. White wants a fast c3 and d4 to build a big center, but Black can take with ...Nxb4 or ...cxb4 and keep the extra pawn safely.

Moves
1.e4 c5 2.Nf3 Nc6 3.b4
ECO
B30
Engine
−0.51 · a slight edge for Black (Stockfish 17.1, depth 20)
Played
932 games in our lichess sample
White scores
54.0%

Key ideas for both sides

White

  • After 3...Nxb4, play c3 to chase the knight, then d4 to build the e4 and d4 center.
  • After 3...cxb4, push d4 and meet ...d5 with exd5 and c4, aiming for quick piece play.
  • Against 3...e5, push b5 to drive the knight away and develop with Bc4 and Nc3.

Black

  • Take with 3...Nxb4; when c3 hits the knight, drop back to c6 and answer d4 with ...cxd4.
  • The 3...cxb4 capture also works: strike at once with ...d5 and use the queen on d5.
  • After the capture, develop with ...e6 and ...Nf6 and keep the extra pawn without grabbing more.

Plans and pawn structure

This gambit is dubious for White. If Black takes with the knight, c3 and d4 give White a full center, but Black keeps an extra pawn and trades on d4 to dissolve it. If Black takes with the c-pawn, d4 and ...d5 open the center, and White's c4 break opens lines while Black's queen stands active. White's compensation is development and space, not material.

What the engine plays from here

Stockfish 17.1 at depth 20 rates the position −0.51: a slight edge for Black. Its three top choices for Black:

  1. −0.51 3...Nxb4 4.c3 Nc6 5.d4 cxd4 6.cxd4
  2. −0.41 3...cxb4 4.d4 d5 5.exd5 Qxd5 6.c4
  3. −0.16 3...e5 4.b5 Nd4 5.Bc4 Nf6 6.Nc3

Pawns, from White's side.

How it scores on lichess

932 rated lichess games reached this position; White scored 54.0%.

1200–159952.5%
1600–199953.9%
2000 and up54.7%

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

How to play against it

As Black, accept the gambit with 3...Nxb4 or 3...cxb4. Trade on d4 when White builds the center, develop calmly, and do not chase extra material with the queen. Return the pawn only if it lets you finish development with a safe king.

Questions

What are the moves of the Sicilian Defense: Portsmouth Gambit?

The Sicilian Defense: Portsmouth Gambit starts 1.e4 c5 2.Nf3 Nc6 3.b4. Its ECO code is B30.

Is the Sicilian Defense: Portsmouth Gambit good for White?

Stockfish 17.1 rates the position −0.51 at depth 20, which is a slight edge for Black. In 932 lichess games from our sample, White scored 54.0%. A surprise weapon at best for White; Black players who take the pawn and develop calmly get the better game.

What is the main idea of the Sicilian Defense: Portsmouth Gambit?

White gives a wing pawn to deflect Black's c-pawn or knight and then builds a center with c3 and d4. Black should take and keep the pawn, trading on d4 to keep White's center small.

What should Black play next?

The engine's first choice is Nxb4, with cxb4 and e5 close behind. 3...Nxb4 wins the pawn with a piece, keeping the c5 pawn to fight against d4.

Updated October 2026. Sources and method.