The Two Knights Defense is an aggressive opening in chess, named for the two knights that are developed in the first three moves by each side.
Its nature makes it perfect for players who prefer tactical battles and a complex middle game.
First documented in the late 16th century, the Two Knights Defense has a rich history and has been adopted by many aggressive players including world champions.
This article will discuss the key aspects of this opening, including the move order, theory and purpose, its variations, and its relevance for different skill levels.
Move Order of the Two Knights Defense
The Two Knights Defense begins with the following moves:
- e4 e5
- Nf3 Nc6
- Bc4 Nf6
It is a line of the Italian Game where Black’s third move signifies a more aggressive defense than the Giuoco Piano (3…Bc5).
Theory, Strategy and Purpose of the Two Knights Defense
The primary strategy behind the Two Knights Defense is to provoke white into an early attack on black’s f7-pawn with 4.Ng5.
By allowing this, black introduces an early tactical battle in the game.
If white takes the bait, black can gain the initiative despite sacrificing a pawn.
The rich tactical complexity of this opening often leads to dynamic positions.
This opening aligns with players who enjoy playing aggressive and tactical positions.
Variations of the Two Knights Defense
Key variations of the Two Knights Defense include:
- Main line: 4.Ng5 d5
- Fritz and Ulvestad’s Variations: 5…Nd4 and 5…b5
- Polerio Defense: 5…Na5
- Traxler Variation: 4…Bc5
- Unsound Variation: 4…Nxe4
- Steinitz Variation: 9.Nh3
- Modern Bishop’s Opening: 4.d3
- Four Knights Variation: 4.Nc3
Each variation leads to different types of middlegame positions, varying from tactical melees to more positional battles.
Let’s look at these variations in more detail:
Main Line: 4.Ng5 d5
Two Knights Defense, Main Line, is an opening that begins with the moves 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5.
This opening sequence can lead to a highly tactical and complex game.
White’s fourth move, 4.Ng5, known as the Knight Attack, is often considered primitive but is highly effective, attacking f7 to almost guarantee the winning of a pawn.
Main Line: 4…d5
In response, Black’s most common move is 4…d5, attacking both the bishop and the e4 pawn.
This forces White to capture the d5 pawn with 5.exd5. Here, Black’s most common move is 5…Na5, called the Polerio Defense.
The Polerio Defense | Black’s main Option in the Two Knights Defense
Other variations for Black include the risky 5…Nxd5 (often leading to the Lolli or Fried Liver Attacks), the Fritz Variation 5…Nd4, and Ulvestad’s Variation 5…b5, which both share a common subvariation and often transpose into each other.
After 5…Na5, White often plays 6.Bb5+, leading to the so-called Knorre Variation if Black responds with 6…c6.
After 7.dxc6 bxc6 8.Be2 h6, the main move for White is 9.Nf3, allowing Black to seize some initiative with 9…e4 10.Ne5 Bd6.
After these ten moves, White’s advantage lies in having an extra pawn and a better pawn structure, despite having fewer developed pieces than Black.
Alternatively, White can play 9.Nh3 (the Steinitz Variation) instead of 9.Nf3, a move once favored by Wilhelm Steinitz, forgotten, and then revived by both Bobby Fischer in the 1960s and Nigel Short in the 1990s.
Apart from 8.Be2, White can also play 8.Qf3 or 8.Bd3, the latter having apparently become fashionable in recent years.
4…Bc5 (Traxler Counterattack or Wilkes-Barre Variation)
The Traxler Variation (or the Wilkes-Barre Variation in the US and UK) is a highly aggressive response to the Two Knights Defense Knight Attack with 4…Bc5.
Named after Karel Traxler and the city of Wilkes-Barre, Pennsylvania (due to Frank Marshall’s contributions), this variation invites wild, complex play.
In response to 4…Bc5, White can opt for three main moves: 5.d4, 5.Nxf7, or 5.Bxf7+:
- If 5.d4, Black can respond with 5…d5, prompting 6.Bxd5 to continue pressure on f7.
- If 5.Nxf7, Black can answer with 5…Bxf2+ leading to a very complex game. The main line thought to lead to balanced or drawn positions proceeds with 6.Kxf2 Nxe4+ 7.Kg1 (or 7.Ke3).
- If White plays 5.Bxf7+, a good reply for Black is 5…Ke7, after which 6.Bb3 is probably White’s best attempt at gaining an advantage. This line poses the most problems for Black.
A tricky side line is 5.Bxf7+ Kf8!? which might lead to a pitfall for White if they proceed with 6.Bb3 d6 7.Nf7 Qe7 8.Nxh8??, since now Black gets an upper hand after 8…Bg4!! 9.f3 Nxe4, exploiting the pinned f3-pawn.
If White blunders with 10.fxg4??, Black wins with 10…Qh4+ 11.g3 Bf2+.
The 4…Nxe4 variation is generally considered unsound, but still requires careful play from White.
After 5.Nxe4 d5, Black has no issues. If White errs with 5.Nxf7? Qh4! 6.g3 (6.0-0 Bc5!), Black can launch a strong attack with 6…Qh3 7.Nxh8 Qg2 8.Rf1 Nd4 9.Qh5+ g6 10.Nxg6 hxg6 11.Qxg6+ Kd8, posing dangerous threats.
The correct response after 4…Nxe4 is 5.Bxf7+! Ke7, followed by 6.d4!
In this variation, White aims for rapid development with 4.d4 exd4 5.0-0.
Now, Black can simply equalize by capturing White’s last central pawn with 5…Nxe4.
After the subsequent 6.Re1 d5 7.Bxd5 Qxd5 8.Nc3, Black can comfortably play either 8…Qa5 or 8…Qh5.
The Nakhmanson Gambit with 6.Nc3 offers White compensation if Black accepts the piece with 6…dxc3 7.Bxf7+ Kxf7 8.Qd5+, but it’s recommended that Black counters with 6…Nxc3 7.bxc3 d5 8.Bb5 Be7 for a better position.
Alternatively, the Max Lange Attack can occur after 5…Bc5 6.e5 d5, leading to extensive analysis.
Modern Bishop’s Opening: 4.d3
The move 4.d3 aims for a quiet game, avoiding the sharp tactical battles in other Two Knights lines.
It is also the best response to the Two Knights Defense according to modern chess engines.
This move is known as the Modern Bishop’s Opening and may transpose into the Giuoco Pianissimo if Black responds with 4…Bc5.
There are also independent lines like 4…Be7 or 4…h6.
Here, White seeks a more positional game, often developing with 6. c3 after castling (5. O-O) and retreating the bishop to c2 (via Bc4–b3–c2).
This move gained popularity in the 1980s and has been utilized by players such as John Nunn.
However, 6. a4 is also a move in lieu of 6. c3.
The Modern Bishop’s Opening of the Italian Game was widely popular in the early-20th century, and has picked up in popularity in recent years with the relative strength that modern chess engines give it.
Four Knights Variation: 4.Nc3
Attempting to defend the e4 pawn with 4.Nc3 is not generally effective, as Black can still capture the pawn and use a fork trick to regain the piece with 4…Nxe4! 5.Nxe4 d5.
The attempt 5.Bxf7+? also doesn’t work well, as Black ends up with the bishop pair and a better position after 5…Kxf7 6.Nxe4 d5.
Typically, 4.Nc3 is played with the intention of gambiting the e-pawn with the Boden–Kieseritzky Gambit, 4.Nc3 Nxe4 5.0-0.
While not common in tournament play due to its dubious reputation in opening theory, it can provide White with decent practical chances, especially in blitz games.
Evaluation of the Two Knights Defense
The Two Knights Defense is generally evaluated at around +0.15 to +0.30 for white.
This assume 4. d3 is played rather than 4. Ng5.
Theory & Continuation Lines of the Two Knights Defense
Below we have some common theory and continuation lines from the Two Knights Defense starting move order 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 that you would see at the highest level of play.
4. d3 is considered the best reply to the Two Knights Defense.
4. Ng5 remains a viable as well, but largely throws away white’s opening advantage.
4. d3 Bc5 5. O-O d6 6. Re1 a6 7. c3 O-O 8. a4 Be6 9. b4 Ba7 10. Bxe6 fxe6 11. Be3 Bxe3 12. fxe3 Qe8 13. Nbd2 Nd8 14. h3 Qh5 15. Qb3 g5 16. Nh2 g4 17. hxg4 Nxg4
4. d3 Bc5 5. O-O d6 6. c3 a5 7. h3 O-O 8. Re1 Be6 9. Bb5 Ne7 10. d4 Ba7 11. Bd3 Ng6 12. Be3 Nh5 13. Bf1 c6 14. g3 h6 15. a4 Nf6 16. Nbd2 Re8 17. dxe5 dxe5
4. d3 Bc5 5. O-O d6 6. c3 a5 7. h3 h6 8. Re1 Ba7 9. Na3 g5 10. Nb5 Bb6 11. Nh2 Rg8 12. Be3 Bxe3 13. Rxe3 Kf8 14. a4 h5
4. d3 Bc5 5. O-O d6 6. c3 a6 7. a4 Ba7 8. Bb3 O-O 9. h3 h6 10. Be3 Ne7 11. Bxa7 Rxa7 12. Re1 b6 13. d4 Ng6 14. Nbd2 c5 15. Bc4 Qc7 16. b4 Bd7 17. Bf1 Re8 18. bxc5 bxc5
4… d5 5. exd5 Na5 6. Bb5+ c6 7. dxc6 bxc6 8. Bd3 Nd5 9. h4 h6 10. Qh5 Qf6 11. Ne4 Qe6 12. Ng5
History of the Two Knights Defense
The Two Knights Defense was first recorded by Giulio Cesare Polerio in the late 16th century.
During the 19th century, it was extensively developed and incorporated into the games of numerous aggressive players, including Mikhail Chigorin and Paul Keres, and world champions Mikhail Tal and Boris Spassky.
In recent times, the Two Knights Defense is less frequently seen in grandmaster play, with 3…Bc5 proving a more common response.
Nevertheless, it remains a popular choice among amateur players.
Is the Two Knights Defense Good for Beginners or Intermediates?
For beginners, the Two Knights Defense may be a challenging opening due to the high level of tactical complexity it can generate.
It requires a solid understanding of chess principles, as well as the ability to navigate complex positions.
On the other hand, the opening can be an excellent tool for intermediate players looking to enhance their tactical abilities.
Playing this opening can help players familiarize themselves with complex tactical scenarios, enhance their calculation skills, and learn to navigate intricate positions.
How Often Is the Two Knights Defense Played at the Grandmaster Level
In modern grandmaster play, the Two Knights Defense is not commonly seen due to its tactical nature and the risk involved.
More solid defenses, like 3…Bc5, are often preferred.
However, it has been employed sporadically in high-level chess games by certain aggressive players.
Though it’s not a primary weapon for most grandmasters, it can be an interesting surprise weapon.
FAQs – Two Knights Defense
1. What is the Two Knights Defense?
The Two Knights Defense is a chess opening that arises from the Italian Game, beginning with the moves:
- e4 e5
- Nf3 Nc6
- Bc4 Nf6
First documented in the late 16th century by Giulio Cesare Polerio, it is an aggressive defense strategy employed by Black, often resulting in a tactical game where Black may sacrifice a pawn for the initiative.
It has been used by many well-known players throughout history, including Mikhail Chigorin, Paul Keres, Mikhail Tal, and Boris Spassky.
While less common in modern grandmaster play, it remains a popular choice among amateur players.
The theory of this opening has been extensively explored in correspondence chess.
2. What is the 4.Ng5 variation?
The 4.Ng5 variation, often considered a “real duffer’s move” or “primitive”, is a White’s attack on the f7-pawn.
The move forces Black into tactical complications and may win a pawn by force.
Despite criticism, it remains a popular choice for White at all levels.
In response, Black often plays 4…d5 and, after White’s 5.exd5, the most common response is 5…Na5.
However, other options are also possible, each with its own set of resulting complexities and potential outcomes.
3. What are the main line and subvariations in the Two Knights Defense?
The main line of the Two Knights Defense typically begins with 4…d5, after which White plays 5.exd5.
Black often responds with 5…Na5, leading to the Polerio Defense. However, other viable subvariations exist, such as the Fritz Variation (5…Nd4) and Ulvestad’s Variation (5…b5), which share a common subvariation.
Each subvariation presents unique opportunities and challenges for both players, adding to the tactical depth of the Two Knights Defense.
4. What is the Traxler Variation?
The Traxler Variation, also known as the Traxler Counterattack or the Wilkes-Barre Variation, begins with 4…Bc5.
It is a bold move by Black that ignores White’s attack on f7 and can lead to aggressive, complex play.
White can respond with 5.d4, 5.Nxf7, or 5.Bxf7+.
Each of these responses leads to different potential outcomes, all of which present substantial challenges for both players.
5. What is the 4…Nxe4 variation in the Two Knights Defense?
The 4…Nxe4 variation is often considered unsound but can lead to interesting positions if handled with care.
After 5.Nxe4, Black can respond with 5…d5, which poses no problems.
However, the move 5.Nxf7 can lead to complicated lines where Black has dangerous threats, particularly after 5…Qh4 and subsequent moves.
The best reply for White to 4…Nxe4 is considered to be 5.Bxf7+ followed by 6.d4.
6. How does the 4.d4 variation of the Two Knights Defense play out?
In the 4.d4 variation, White aims for rapid development.
After 4.d4 exd4 5.0-0, Black can either eliminate White’s last center pawn with 5…Nxe4 or enter the extensively analyzed Max Lange Attack after 5…Bc5 6.e5 d5.
This variation can also result from transpositions from the Giuoco Piano or Scotch Game.
White can avoid these lines by playing 5.e5, a line often adopted by Sveshnikov.
7. What is the Modern Bishop’s Opening in the Two Knights Defense?
The Modern Bishop’s Opening is a quiet variation of the Two Knights Defense that starts with 4.d3.
It can transpose into the Giuoco Pianissimo if Black responds with 4…Bc5, but independent variations exist after 4…Be7 or 4…h6.
This move became popular in the 1980s and is often chosen by players who prefer to avoid the tactical battles common in other lines of the Two Knights Defense.
8. What is the Four Knights Variation in the Two Knights Defense?
The Four Knights Variation in the Two Knights Defense begins with 4.Nc3.
While this move attempts to defend the e4 pawn, it doesn’t work well as Black can take the pawn anyway using a fork trick.
The main intent of 4.Nc3 is often to gambit the e-pawn with the Boden–Kieseritzky Gambit, 4.Nc3 Nxe4 5.0-0.
This gambit is less common in tournament play due to its lower regard in opening theory but can offer good practical chances, particularly in blitz chess.
The Two Knights Defense is a dynamic and aggressive chess opening.
While it may not be a common sight in modern grandmaster play, its rich history and the exciting tactical battles it offers make it a fascinating choice.
Ideal for players who enjoy complex, tactical positions, it serves as an excellent learning tool for improving players.
Whether you’re an amateur or an intermediate player, exploring the Two Knights Defense can add a powerful weapon to your chess repertoire.