Play the King's Gambit Declined: Queen's Knight Defense (Bc4) as Black

The King's Gambit is all about attacking chances for White, but in this line you've already pocketed a pawn on f4. Stockfish gives -0.64, a small plus for Black, so you are slightly better. That evaluation comes with a warning: your advantage depends on solid development, not greed. The engine's top choice after 3...exf4 is 4.d4, and it recommends you answer with 4...Nf6, bringing out a knight and threatening ...Nxe4. After 5.Nc3, the engine line continues 5...Bb4, pinning the knight and keeping the extra pawn secure. Notice the pattern: develop actively, don't rush to hang onto the f4-pawn at all costs, and make White's life difficult by targeting e4.

This position has been played nearly half a million times in the Lichess database. The overall results show White winning 53.8%, draws 2.7%, and Black winning 43.5%. That's a solid score for Black given you're playing a gambit defence, but White's win rate is higher than you might expect for a position that favours Black. Why? Because many Black players go wrong in the next few moves. The most popular reply is 4.Nf3 (322,156 games), where White scores 54.4%. The engine's choice, 4.d4, is second-most popular (78,761 games) and actually scores slightly higher for White at 55.0%. That's an important takeaway: even the engine's best move is dangerous if you don't know the follow-up. But the real opportunities for you come when White plays something suboptimal — and there are several common candidates.

When White strays from 4.d4, you gain real chances. Here are the three most common errors, ranked by how much they cost White: d3 is a mistake, losing about 1.1 pawns. White can try 4.d3, but it's too timid — you keep your extra pawn with healthy development. Nc3 is an inaccuracy, losing about 0.7 pawns. 4.Nc3 develops a piece but doesn't challenge your grip on f4. You can simply continue ...Nf6 or ...Bb4 with a comfortable game. Bxf7+ is the worst of the bunch — a full-blown mistake costing White roughly 2.8 pawns. This check may look tempting at first glance, but after 4...Kxf7 you have the bishop pair, an open king but one that's safe enough, and a clean extra pawn. Each of these moves appears thousands of times in the database, so be ready to pounce when White plays them.

By far the most common move here is 4.Nf3, appearing in over 322,000 games. While it's not the engine's top pick — that honour goes to 4.d4 — White still scores a respectable 54.4% with it. Your plan is straightforward: develop naturally with ...Nf6, preparing to castle kingside and keeping the f4-pawn intact. Watch out for ideas like Ng5 or Bxf7+ tricks, but as long as you stay alert, your extra pawn and active pieces should carry the day. The drill below will let you practise this exact position against an adapting engine, so you can build the reflexes to handle 4.Nf3, 4.d4, and everything else White throws at you.