Two Knights Defense

Two Knights Defense

a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h
Moves	1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6
ECO	C55–C59
Origin	Late 16th century
Parent	Italian Game
Synonym(s)	Prussian Defense[1]

The Two Knights Defense (also called the Prussian Defense) is a chess opening that begins with the moves:

1. e4 e5

2. Nf3 Nc6

3. Bc4 Nf6

First recorded by Giulio Cesare Polerio^[2] (c. 1550 – c. 1610) in the late 16th century, this line of the Italian Game was extensively developed in the 19th century. Black's third move is a more aggressive defense than the Giuoco Piano (3...Bc5). White may attack Black's weak pawn on f7 with 4.Ng5. If White does so, the game quickly takes on a tactical character: Black is practically forced to give up a pawn for the initiative. The complications are such that David Bronstein suggested that the term "defense" does not fit, and that the name "Chigorin Counterattack" would be more appropriate.^[3] However, White most often opts for the quieter 4.d3. The Two Knights has been played and analyzed by many aggressive players including Mikhail Chigorin, Paul Keres, and world champions Mikhail Tal and Boris Spassky.

4.Ng5

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Knight Attack: 4.Ng5

This move creates a double attack on Black's pawn on f7, as White's bishop on c4 also targets the square. If the knight were to capture the pawn, this would fork Black's queen and rook. If the bishop were to capture instead, Black's king would be forced to move and lose castling rights. As Black cannot soundly reinforce the pawn, the usual response is 4...d5, obstructing White's bishop's line of attack. Although the move practically wins a pawn by force, Black can gain compensation with precise play through quick development and gaining tempo by forcing White's pieces to retreat. An alternative for Black is to counterattack with 4...Bc5, permitting White to capture the pawn.

This sharp line was very common in the 19th century during the era of Romantic chess, but attracted criticism. The German master Siegbert Tarrasch called 4.Ng5 "a real bungler's move" (ein richtiger Stümperzug)^[4] and Soviet opening theorist Vasily Panov called it "primitive". It was not well regarded in the 20th century, and the alternative 4.d3 became the most frequent move, and this remains true today. However, the line was revitalized starting in the 1990s, most notably by Alexander Morozevich and Nigel Short.^[5] It remains a popular option for White, particularly in casual play, and has been employed by world champions Wilhelm Steinitz, Bobby Fischer, Anatoly Karpov, Garry Kasparov, and Viswanathan Anand.

Main Line: 4...d5 5.exd5

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Two Knights Defense, Main Line, 5.exd5 Na5 6.Bb5+ c6 7.dxc6 bxc6

After 4...d5 White has little option but to play 5.exd5, since both the bishop and e4-pawn are attacked. Then Black most often plays 5...Na5, and play usually continues 6.Bb5+ c6 (6...Bd7 is also possible^[6]) 7.dxc6 bxc6 (7...Nxc6 is possible but inferior), with 6.d3 as White's main alternative.

5...Na5 6.Bb5+ c6 7.dxc6 bxc6

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Knorre Variation, 8.Be2 h6 9.Nf3 e4 10.Ne5 Bd6 11.d4 Qc7 12.Bd2

This is the usual continuation of the main line. Following this, White then most commonly plays 8.Be2 (the old main line, still frequent), 8.Qf3 (the Bogoljubow Variation), or 8.Bd3 (the modern main line).

Following 8.Be2, the usual continuation is h6 9.Nf3 e4 10.Ne5. White is behind in development but has an extra pawn as well as a better pawn structure. 10...Bd6 is Black's most common next move, and White usually replies with 11.d4, though 11.f4 is an alternative. One possible line is the Knorre Variation, continuing 11...Qc7 12.Bd2, although 11...exd3 (en passant) and 11...0-0 are more usual for Black.

Alternatives for Black include 10...Bc5, 10...Qc7, the Göring Variation, and 10...Qd4. An alternative for White is 9.Nh3, known as the Steinitz Variation. Although it did not bring Steinitz (who favored it) success in his famous 1891 cable match against Mikhail Chigorin, Bobby Fischer revived it in the 1960s. Nigel Short led a second revival of 9.Nh3 in the 1990s, and today it is thought to be about equal in strength to the more common 9.Nf3.^[6]

Kieseritzky Variation: 5...Na5 6.d3

Instead of retreating the bishop, White may instead play to hold the gambit pawn with this move. Paul Morphy preferred this line, named after Lionel Kieseritzky and also known as the Morphy Variation. It is relatively unpopular since Black obtains good chances for the pawn with 6...h6 7.Nf3 e4 8.Qe2 Nxc4 9.dxc4 Bc5 and White effectively concedes the bishop pair. David Bronstein once tried the piece sacrifice 8.dxe4!? with success, but its soundness is doubtful.^[3][7]

Fritz Variation: 5...Nd4

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Fritz Variation, Main Line, 5.exd5 Nd4 6.c3 b5 7.Bf1 Nxd5 8.cxd4 Qxg5 9.Bxb5+ Kd8 10.0-0 Bb7 11.Qf3 Rb8

German master Alexander Fritz (1857–1932) suggested this move to Carl Schlechter, who wrote about the idea in a 1904 issue of Deutsche Schachzeitung. In 1907 Fritz himself wrote an article about his move in the Swedish journal Tidskrift för Schack. White's best reply is 6.c3, where the game usually continues 6...b5 7.Bf1 Nxd5, followed by 8.cxd4, 8.Ne4, or 8.h4. White may instead play 6.d6, resuming the double attack on f7. Black usually responds with 6...Qxd6, apparently allowing a fork of Black's queen and rook by the knight, but in the line 7.Nxf7? Qc6, White cannot protect the pawn on g2 without giving up the bishop on c4 or allowing the fork Nxc2+, a similar theme to the line with 6...Qxd5? mentioned earlier. If White ignores the threat, such as with 8.Nxh8 Qxg2 9.Rf1, Black wins White's queen after 9...Qe4+ or 9...Bg4. Magnus Carlsen and Gukesh Dommaraju played a game in this variation in 2024.^[8]

The Berliner Variation, named in honor of IM / GMC Dr. Hans Berliner, continues the Fritz sub-line 8.Ne4 with 8...Qh4, from the famous game Estrin–Berliner, World Correspondence Championship 1965–68, eventually won by Black; this win was pivotal to Berliner's eventual championship victory. That game, which saw Black embark on a very sharp sacrificial path, continued 9.Ng3 Bg4 10.f3 e4 11.cxd4 Bd6 12.Bxb5+ Kd8 13.0-0 exf3. In 1971, IM / GMC Estrin later published a suggestion of the move 14.Qb3!? as an improvement on the game continuation, and this possibility has continued to interest many players.^[9]

5...Nxd5?!

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Fried Liver Attack, Main Line, 6.Nxf7 Kxf7+ 7.Qf3+ Ke6 8.Nc3

This recapture is extremely risky. Albert Pinkus tried to bolster this move with analysis in 1943 and 1944 issues of Chess Review, but White gets a strong attack with either the safe Lolli Attack (6.d4), which Bobby Fischer thought to be very strong,^[10] or the sacrificial Fried Liver Attack (6.Nxf7), which usually continues 6...Kxf7 7.Qf3+ Ke6 8.Nc3, leaving Black's king almost in the middle of the board. These variations are usually considered too difficult for Black to defend over the board, but they are still occasionally played. Lawrence Trent describes 5...Nxd5 as "a well-known bad move" (or words to that effect).^[6]

Ulvestad Variation: 5...b5

This line is related to the Fritz Variation as they share a common subvariation. American master Olav Ulvestad introduced 5...b5 in a 1941 article in Chess Review.^[11] White has only one good reply, the unnatural 6.Bf1! (6.Bd3?! is weak to 6...Bf5), protecting the undefended pawn on g2, so White can answer 6...Qxd5? with 7.Nc3. Both replies 6.Bxb5 Qxd5 7.Bxc6+ Qxc6 and 6.dxc6 bxc4 7.Nc3 are weak for White. After 6.Bf1!, Ulvestad's first idea 6...h6? is refuted by 7.Nxf7!.^[12] Black's best response is 6...Nxd5, which is Ulvestad’s second idea.^[13] Black can also transpose to the Fritz Variation with 6...Nd4, making another advantage of 6.Bf1 apparent; the bishop is not attacked as it would be if White had played 6.Be2.

Traxler Variation: 4...Bc5

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Traxler or Wilkes-Barre Variation

Main article: Two Knights Defense, Traxler Counterattack

This bold move ignores White's attack on f7 and leads to wild play. Czech problemist Karel Traxler played it against Reinisch in Prague in 1890.^[14] Later it was named after Wilkes-Barre, Pennsylvania by Frank Marshall, who claimed to be first to analyze and publish it,^[15] so today 4...Bc5 is known as both the Traxler Variation and (in the United States and the United Kingdom^[16] only) the Wilkes-Barre Variation.

White can play 5.d4, 5.Nxf7, or 5.Bxf7+:

• After 5.d4 d5!, White's best move is 6.Bxd5, reapplying the pressure on f7.
• 5.Nxf7 is very complicated after 5...Bxf2+. The current main lines all are thought to lead to drawn or equal positions, e.g. after 6.Kxf2 Nxe4+ 7.Kg1, or even 7.Ke3.
• White's best try for an advantage is probably 5.Bxf7+ Ke7 6.Bb3 (although 6.Bd5 was the move recommended by Lawrence Trent),^[6] as this poses Black the most problems. No grandmasters have regularly adopted the Wilkes-Barre as Black, but Alexander Beliavsky and Alexei Shirov have played it occasionally even in top competition. Belyavsky even ventured it twice, holding then-World Champion Karpov to a draw and defeating Anand.^[17][18] No clear refutation is known.
  A tricky variation is 5.Bxf7+ Kf8!?, where Black plays for one last trick with 6.Bb3 d6 7.Nf7 Qe7. If White plays the seemingly standard 8.Nxh8??, Black is now winning after 8...Bg4!! 9.f3 Nxe4, making use of the pinned f3-pawn. This pawn cannot capture the bishop as 10.fxg4?? Qh4+ 11.g3 Bf2+ wins by force for Black.

Ponziani-Steinitz Gambit: 4...Nxe4

4...Nxe4?! is considered unsound but must be handled carefully. 5.Nxe4 d5 poses no problems for Black. If 5.Nxf7? Qh4! 6.g3 (6.0-0 Bc5!) 6...Qh3 7.Nxh8 Qg2 8.Rf1 Nd4 9.Qh5+ g6 10.Nxg6 hxg6 11.Qxg6+ Kd8 and Black has dangerous threats.^[19] (Alternatively, after 5.Nxf7? Qh4! 6.g3, Black could play more aggressively 6...Nxg3! 7.fxg3 Qe4+ 8.Qe2 Qxh1+ 9.Qf1 Qxf1+ 10.Kxf1 d5 11.Bxd5 Bh3+ 12.Ke1 Nb4 13.Bb3 Nxc2+ 14.Bxc2 Kxf7 with a distinct advantage of material for Black.) Correct is 5.Bxf7+! Ke7 6.d4! (6.d3 is also good) and now:

• 6...d5 7.Nc3! (best, discovered by Soviet player Lopukhin; White has a clear advantage) 7...Nxc3 8.bxc3 Qd6 (8...Bf5 9.Qf3±; 8...e4 9.f3!) 9.a4! Kd8 10.Bg8! Ke8 11.Bxh7± (Estrin).^[20][19]
• 6...h6 7.Nxe4 Kxf7 and now 8.dxe5 Qe8 9.f4 d6 10.0-0 (±) Kg8 11.Nbc3 dxe5 12. f5 Qf7 13.Nd5 Bd7 14.f6 g6 15.Ne7+! and White has excellent chances (Estrin).^[20][19]

Open Variation: 4.d4

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Max Lange Attack

White can choose to develop rapidly with 4.d4 exd4 5.0-0. Now Black can equalize simply by eliminating White's last center pawn with 5...Nxe4, after which White regains the material with 6.Re1 d5 7.Bxd5 Qxd5 8.Nc3, but Black has a comfortable position after 8...Qa5 or 8...Qh5.

The wild Nakhmanson Gambit 6.Nc3 gives White compensation if Black accepts the piece with 6...dxc3 7.Bxf7+ Kxf7 8.Qd5+ and then makes the intuitive move 8...Ke8?! Instead, 8...Kf6! has been analyzed to offer Black a substantial edge with best play. Victor Bologan suggests declining the gambit with 6...Nxc3 7.bxc3 d5 8.Bb5 Be7 leading to a better position for Black.^[21]

Alternatively, Black can enter the extensively analyzed Max Lange Attack after 5...Bc5 6.e5 d5, which can also arise by transposition from the Giuoco Piano or Scotch Game. White can choose to avoid these lines by playing 5.e5, a line often adopted by Sveshnikov. After 5.e5, either 5...Ne4 or 5...Ng4 is a playable reply, but most common and natural is 5...d5 6.Bb5 Ne4 7.Nxd4 Bc5, with sharp play. The tricky 5.Ng5?! is best met by 5...d5! 6.exd5 Qe7+!

Modern Bishop's Opening: 4.d3

The quiet 4.d3 is White's most common fourth move and is known as the Modern Bishop's Opening.^[22] By playing d3, White tries to avoid the tactical battles that are common in other lines of the Two Knights and to enter a more positional game. The resulting positions take on some characteristics of the Ruy Lopez if White plays c3 and retreats the bishop to c2 via Bc4–b3–c2. This move became popular in the 1980s and has been used by John Nunn and others.

Black can and often does transpose into the Giuoco Pianissimo by playing 4...Bc5, but there are also independent variations. The other most common responses by Black are 4...Be7 and 4...h6, which often lead to closed, positional games. Another option is for Black to open the game with 4...d5, a dynamic but risky line.

Four Knights Variation: 4.Nc3

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Boden–Kieseritzky Gambit

Further information: Four Knights Game § 4.Bc4

The attempt to defend the pawn with 4.Nc3 does not work well since Black can take the pawn anyway and use a fork trick to regain the piece, 4.Nc3?! Nxe4! 5.Nxe4 d5. The try 5.Bxf7+? does not help, as Black has the bishop pair and a better position after 5...Kxf7 6.Nxe4 d5. Instead, 4.Nc3 is usually played with the intent to gambit the e-pawn with the Boden–Kieseritzky Gambit, 4.Nc3 Nxe4 5.0-0. This gambit is not commonly seen in tournament play as it is not well regarded by opening theory, but it can offer White good practical chances, especially in blitz chess.

References

1. Hooper & Whyld (1996), p. 324. Prussian Defence.
2. Y. Estrin (1983). The Two Knights Defence. Batsford. ISBN 0-7134-3991-2.
3. Bronstein, David (1991) [1973]. 200 Open Games. Dover. pp. 60–61. ISBN 0-486-26857-8.
4. Tarrasch 1935, p. 259.
5. Pinski, Jan (2004). The Two Knights Defence. Everyman Chess. ISBN 1-85744-283-0.
6. "Two Knight's Defence". chessbase-shop.com. Archived from the original on 2011-11-29.
7. "Bronstein vs. Rojahn, Moscow Olympiad 1956". Chessgames.com. Archived from the original on 2007-12-15. Retrieved 2005-11-19.
8. "Dommaraju Gukesh vs. Magnus Carlsen, Warsaw, Superbet rapid, 2024". Chessgames.com. Retrieved 8 August 2025.
9. Nunn's Chess Openings. London: Everyman Chess. 1999. section on Two Knights' Defense.
10. Fischer, Bobby. My 60 Memorable Games. Fischer's analysis of this line is in game 45, Fischer–Bisguier, 1963
11. Ulvestad, Olaf I. (January 1941). "A New Move in an Old Defense". Chess Review. pp. 7–8 – via Internet Archive.
12. "Francisco Valleo Pons vs. Arkadij Naiditsch, 16th European Team Chess Championship, 2007". Chessgames.com. Retrieved 8 August 2025.
13. Tait 2022, p. 256.
14. "J. Reinisch vs. Karel Traxler, Hostoun 1890". Chessgames.com. Archived from the original on 2019-03-13. Retrieved 2019-03-24.
15. Hooper & Whyld (1996), p. 448. Wilkes-Barre variation.
16. Elburg, John (2002). "New in Chess Year book issue 65". Chessbook Reviews. Chess Books. Archived from the original on 2010-09-24. Retrieved 2010-04-30.
17. "Anatoly Karpov vs. Alexander Beliavsky, 16th Soviet Team Championship, Moscow, 1983". Chessgames.com. Retrieved 8 August 2025.
18. "Vishwanathan Anand vs. Alexander Beliavsky, Linares, 1991". Chessgames.com. Retrieved 8 August 2025.
19. Harding & Botterill (1977), p. 66
20. Estrin (1971), p. 67
21. Bologan, Victor (2014). Bologan's Black Weapons in the Open Games. The Netherlands: New in Chess. p. 450. ISBN 9789056915438.
22. Hooper & Whyld (1996), p. 262. Modern Bishop's Opening.

Bibliography

• de Firmian, Nick (1999). Modern Chess Openings: MCO-14. Random House Puzzles & Games. ISBN 0-8129-3084-3.
• Estrin, Yakov (1971). The Two Knights' Defence (English ed.). Chess Ltd.
• Harding, Tim; Botterill, G. S. (1977). The Italian Game. B. T. Batsford Ltd. ISBN 0-7134-3261-6.
• Hooper, David; Whyld, Kenneth (1996) [First pub. 1992]. The Oxford Companion to Chess (2nd ed.). Oxford University Press. ISBN 0-19-280049-3.
• New in Chess Yearbook 55. New in Chess. 2000. ISBN 90-5691-069-8.
• Pinski, Jan (2003). The Two Knights Defence. Everyman Chess. ISBN 1-85744-283-0.
• Tait, Jonathan (2022). A Disreputable Opening Repertoire. Everyman Chess. ISBN 978-1781946060.
• Tarrasch, Siegbert (1935). The Game of Chess. London: Chatto & Windus – via Internet Archive.
• Unzicker, Wolfgang (1975). Knaurs Neues Schachbuch für Anfänger und Fortgeschrittene. Droemer Knaur. ISBN 3-426-02242-7.

Further reading

• Beliavsky, Alexander; Mikhalchishin, Adrian (1999). The Two Knights Defense. Batsford. ISBN 978-0-7134-8441-0.
• Tait, Jonathan (2004). The Two Knights Defence. Everyman Chess. ISBN 978-1857442830.

External links

• Harding, Tim (March 2001). The Kibitzer: Two Knights Defense, Part 1 (PDF). Chesscafe.com.
• Harding, Tim (April 2001). The Kibitzer: Two Knights Defense, Part 2 (PDF). Chesscafe.com.
• Harding, Tim (May 2001). The Kibitzer: Two Knights Defense, Part 3 (PDF). Chesscafe.com.