- The moves1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6
- Chosen byBlack
- ECOC55–C59
- Also calledPrussian Defense
The Two Knights Defense comes after 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6. Instead of mirroring White's bishop move with 3…Bc5, as in the Italian Game, Black develops another knight and attacks the pawn on e4. White can answer sharply with 4.Ng5, against f7, or quietly with 4.d3.
The opening was analyzed as early as the 1500s by the Italian Giulio Cesare Polerio. Its old name, the Prussian Defense, points to the German masters who studied it thoroughly in the first half of the 1800s, above all Paul Rudolph von Bilguer.
In the 1800s Mikhail Chigorin showed that Black gets good play for the pawn that is lost in the main line. Siegbert Tarrasch called 4.Ng5 “a duffer's move,” yet it has been played by world champions such as Wilhelm Steinitz, Bobby Fischer, Anatoly Karpov and Garry Kasparov. David Bronstein felt that the word defense fitted badly, since Black so often attacks, and suggested Chigorin Counterattack instead.
The main line, move by move
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5 Na5 6. Bb5+ c6 7. dxc6 bxc6 8. Be2 h6 9. Nf3 e4 10. Ne5 Bd6 11. d4 exd3 12. Nxd3 Qc7 13. b3 O-O 14. Bb2
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.
- 7.
- 8.
- 9.
- 10.
- 11.
- 12.
- 13.
- 14.…
The ideas
White wants to
- Attack f7 with Ng5, preferably on move four, and try to keep the pawn it wins.
- Or play quietly with d3 and get a position like the Italian Game.
- Against 5…Nxd5: sacrifice on f7 and hunt the king into the open.
Black wants to
- Attack e4 and seize the initiative instead of waiting.
- Against 4.Ng5: play 4…d5 and give a pawn for quick development and open lines.
- If you dare more, play Traxler's 4…Bc5, which leaves f7 alone and strikes back at f2.
Important variations
The Fried Liver: 5…Nxd5? 6.Nxf7
If Black recaptures with 5…Nxd5, the sacrifice 6.Nxf7! follows. Black's king is drawn into the open, and after 7.Qf3+ Ke6 8.Nc3 White has a dangerous attack. It has not been proven to win, but defending at the board is hard, especially with little time on the clock. In Italian it is called the fegatello, after a dish. The idea has been known for centuries: the earliest example is a game by Polerio from before 1606. Bobby Fischer thought 6.d4 was very strong.
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5 Nxd5 6. Nxf7 Kxf7 7. Qf3+ Ke6 8. Nc3 Nb4 9. O-O c6
The Traxler Counterattack: 4…Bc5
Black ignores the threat to f7 and strikes back at f2. Karel Traxler, a Czech problem composer, played it in 1890. Frank Marshall later named it after the town of Wilkes-Barre in Pennsylvania, and in the United States and Britain it still goes by that name. No clear refutation is known. Today most masters answer with 5.Bxf7+, which wins a pawn and avoids the complications after 5.Nxf7. The trap below shows why they avoid them.
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 Bc5 5. Bxf7+ Ke7 6. Bd5 Rf8
4… Bc5
The Traxler Counterattack. Black leaves f7 alone and aims at f2.
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.
The quiet 4.d3
Today 4.d3 is White's most common move. White protects e4 and sidesteps the sharp lines. If Black answers 4…Bc5, it has become the Giuoco Pianissimo, the Italian Game at its quietest. With 4…Be7 the game is quieter still, and both sides build up in peace.
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d3 Be7 5. O-O O-O 6. Re1 d6 7. a4
4. d3
White protects the pawn on e4 and aims for a quiet game.
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.
- 7.…
The trap: the rook on h8 in the Traxler
Against Traxler's 4…Bc5, 5.Nxf7 looks natural: the knight forks the queen and the rook. But Black sacrifices 5…Bxf2+!, and after 6.Kxf2 Nxe4+ 7.Ke3 Qh4 White's king stands in the middle of the board. White now has to defend, and the only move that holds is 8.g3. Take the rook with 8.Nxh8?? instead, and it is mate in four. It is a common mistake among beginners.
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 Bc5 5. Nxf7 Bxf2+ 6. Kxf2 Nxe4+ 7. Ke3 Qh4 8. Nxh8 Qf4+ 9. Ke2 Qf2+ 10. Kd3 Nb4+ 11. Kxe4 Qf4#
11… Qf4#
… and is mated in the middle of the board.
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.
- 7.
- 8.
- 9.
- 10.
- 11.
How it goes in real games
How the games ended once the position had come up on the board, in blitz, rapid and classical games. White wins, draws and Black wins, as a percentage of the games.
| Position | Level | Games | White wins | Draw | Black wins |
|---|---|---|---|---|---|
| Two Knights Defense 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 | Club players | 35,061,500 | 50% | 4% | 46% |
| Strong players | 6,864,592 | 48% | 5% | 47% | |
| Two Knights Defense, main line, up to 10.Ne5 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5 Na5 6. Bb5+ c6 7. dxc6 bxc6 8. Be2 h6 9. Nf3 e4 10. Ne5 | Club players | 274,152 | 46% | 4% | 49% |
| Strong players | 98,906 | 45% | 5% | 50% | |
| The Fried Liver: 5…Nxd5? 6.Nxf7, up to 8…Nb4 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5 Nxd5 6. Nxf7 Kxf7 7. Qf3+ Ke6 8. Nc3 Nb4 | Club players | 227,437 | 55% | 3% | 42% |
| Strong players | 22,722 | 52% | 3% | 45% | |
| The Traxler Counterattack: 4…Bc5, up to 5…Ke7 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 Bc5 5. Bxf7+ Ke7 | Club players | 328,482 | 48% | 3% | 49% |
| Strong players | 111,094 | 47% | 4% | 49% | |
| The quiet 4.d3, up to 5…O-O 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d3 Be7 5. O-O O-O | Club players | 924,264 | 48% | 6% | 46% |
| Strong players | 341,914 | 49% | 7% | 45% |
The most common continuations after 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6
Club players, share of the games in the position.
- 4.d3 33% (11,469,866 games)
- 4.Ng5 29% (10,101,301 games)
- 4.Nc3 14% (4,754,645 games)
- 4.O-O 12% (4,365,971 games)
- 4.d4 8% (2,971,961 games)
Source: games on Lichess, fetched November 6–7, 2026. Club players means games where the players average 1600 or more, strong players games where they average 2000 or more. The strong players' games are counted among the club players' too. Each position is counted however it was reached, and a line that goes further than we have numbers for is shown up to its last position with numbers.
Explore the position on the analysis board: the moves club players choose from here, how the games tend to end, and what Lavi thinks of each move.
Is this opening for you?
The Two Knights Defense suits Black players who would rather seize the initiative than wait for it. It is also one of the best ways to learn tactics with Black: against 4.Ng5 it is about giving a pawn for development, and whoever dares the Traxler gets games decided in a few moves.
With White it is just as instructive. If you want a fight, play 4.Ng5 and learn to hold on to a pawn under pressure. If you would rather avoid theory, play 4.d3 and get a quiet Italian Game.
Practice the main line
Choose a color and one of the house players. Your opponent follows the main line, and you try to find your moves. If you play something else, you'll see the main line's move, but the game goes on. When the main line ends, you play freely.
Rather play freely? Choose an opponent · Play right away
The main line with all the comments as text
1. e4 e5 2. Nf3 Nc6 3. Bc4 The Italian Game. The bishop aims at f7. 3… Nf6 This is the Two Knights Defense. Black attacks the pawn on e4 instead of mirroring White's bishop move. 4. Ng5 The sharpest reply: two pieces against f7. Siegbert Tarrasch called it “a duffer's move,” because White moves a piece that is already out instead of developing. But in practice it wins a pawn. 4… d5 The usual defense. The pawn blocks the bishop's path to f7. 5. exd5 White captures, and now Black can't simply take back. 5… Na5 The knight attacks the bishop before White can keep the attack going. Black gives a pawn for time and development, an idea Mikhail Chigorin showed to be sound. 6. Bb5+ The bishop escapes with check. 6… c6 7. dxc6 bxc6 Black has given a pawn but has open lines and faster development. 8. Be2 The old main move. Today many prefer 8.Bd3. 8… h6 The knight on g5 is driven back. 9. Nf3 The knight retreats. 9.Nh3, which Steinitz played, is an alternative. 9… e4 With tempo: the knight has to move again. 10. Ne5 The knight finds a square in the center. White has an extra pawn and the better pawns, Black has two isolated pawns but leads in development. 10… Bd6 Black's most common move. The bishop attacks the knight on e5. 11. d4 White wants to protect the knight with the pawn. 11… exd3 En passant! The pawn on e4 captures the pawn that just went past it, exactly as if it had only gone to d3. Read more about the rule. 12. Nxd3 White recaptures with the knight. 12… Qc7 The queen and the bishop on d6 aim together at h2. 13. b3 White prepares Bb2 and at the same time takes the c4-square away from Black's knight. 13… O-O 14. Bb2 White has the pawn but is behind in development, Black has active pieces, and the position is roughly equal.
More openings
Italian Game
The bishop to c4 aims at f7. Classical, logical and perfect to learn first.
Evans Gambit
White sacrifices the b-pawn for tempo and the center. Romantic chess from the 1800s.
Scotch Game
3.d4 at once: an open game, free pieces and no long maneuvering.
Vienna Game
The queen's knight first, then perhaps f4. The sharp play of the King's Gambit, with an extra piece developed.
Every move on this page has been checked against the rules of chess.
Updated November 6, 2026
3… Nf6
This is the Two Knights Defense. Black attacks the pawn on e4 instead of mirroring White's bishop move.