The Two Knights Defense is a chess opening

Chess opening

A chess opening is the group of initial moves of a chess game. Recognized sequences of opening moves are referred to as openings as initiated by White or defenses, as created in reply by Black. There are many dozens of different openings, and hundreds of named variants. The Oxford Companion to...

 that begins with the moves:

1. e4 e5

2. Nf3 Nc6

3. Bc4 Nf6

First recorded by Polerio

Giulio Polerio

Giulio Cesare Polerio , was an Italian chess theoretician and player....

(c.1550–c.1610) in the late 16th century, this line of the Italian Game

Italian Game

The Italian Game is a family of chess openings beginning with the moves:The game's defining move is the White king's bishop's move to c4 in preparation for an early attack on Black's vulnerable f7-square. As such the game is typified by aggressive play, where Black's best chances are often...

 was extensively developed in the 19th century.
Black's third move is a more aggressive defense than the Giuoco Piano

Giuoco Piano

The Giuoco Piano is a chess opening beginning with the moves:Common alternatives to 3...Bc5 include 3...Nf6 , 3...Be7 , or 3...d6 .-History:...

 which would result from 3...Bc5.
In fact, Bronstein

David Bronstein

David Ionovich Bronstein was a Soviet chess grandmaster, who narrowly missed becoming World Chess Champion in 1951. Bronstein was described by his peers as a creative genius and master of tactics...

 suggested that the term "defense" does not fit,
and that the name "Chigorin Counterattack" would be more appropriate.
The Two Knights has been adopted as Black by many aggressive players including Chigorin

Mikhail Chigorin

Mikhail Ivanovich Chigorin also was a leading Russian chess player...

 and Keres

Paul Keres

Paul Keres , was an Estonian chess grandmaster, and a renowned chess writer. He was among the world's top players from the mid-1930s to the mid-1960s....

, and World Champions

World Chess Championship

The World Chess Championship is played to determine the World Champion in the board game chess. Men and women of any age are eligible to contest this title....

 Tal

Mikhail Tal

Mikhail Tal was a Soviet–Latvian chess player, a Grandmaster, and the eighth World Chess Champion.Widely regarded as a creative genius, and the best attacking player of all time, he played a daring, combinatorial style. His play was known above all for improvisation and unpredictability....

 and Boris Spassky

Boris Spassky

Boris Vasilievich Spassky is a Soviet-French chess grandmaster. He was the tenth World Chess Champion, holding the title from late 1969 to 1972...

.
The theory of this opening has been explored extensively in correspondence chess

Correspondence chess

Correspondence chess is chess played by various forms of long-distance correspondence, usually through a correspondence chess server, through email or by the postal system; less common methods which have been employed include fax and homing pigeon...

 by players such as Berliner

Hans Berliner

Hans Jack Berliner , a Professor of , is a former World Correspondence Chess Champion, from 1965–68. He is a Grandmaster of Correspondence Chess, and an International Master for over-the-board chess. He directed the construction of the chess computer HiTech. Berliner is also a chess writer.-Life...

 and Estrin

Yakov Estrin

Yakov Borisovich Estrin was a Russian chess International Master, theoretician, and writer.After a brief foray into "over-the-board" play, he turned to correspondence chess in the early 1960s with immediate success Yakov Borisovich Estrin (April 21, 1923 – February 2, 1987) was a Russian chess...

.

Main variations

White must respond to the attack on his e-pawn (For explanation of notation, see Chess Opening Theory Table

Chess opening theory table

A chess opening theory table or ECO table presents lines of moves, typically from the starting position. Notated chess moves are presented in the table from left to right...

).

1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6

	4	5	6	7	8	9	10
Wilkes-Barre or Traxler Variation	Ng5 Bc5!?	Bxf7+! Ke7	Bb3! -	- -	- -	- -	- -
Lolli Variation	... d5	exd5 Nxd5?!	d4! -	- -	- -	- -	- -
Fried Liver Attack Fried Liver Attack The Fried Liver Attack, also called the Fegatello Attack , is a chess opening. This colourfully named opening is a variation of the Two Knights Defense in which White sacrifices a knight for a superficially impressive attack on Black's king...	... ...	... ...	Nxf7!? Kxf7	Qf3+ Ke6	Nc3 Nb4	a3! Nxc2+	Kd1 Nxa1	- -
Morphy Variation	... d5	exd5 Na5	d3 h6	Nf3 e4	Qe2 Nxc4	dxc4 Bc5	- -
Main Line	... ...	... ...	Bb5+ c6	dxc6 bxc6	Be2 h6	Nf3 e4	Ne5 -
Steinitz Variation	... ...	... ...	... ...	... ...	... ...	Nh3 -	- -
Ulvestad Variation	... ...	... b5	Bf1! Nd4	c3 Nxd5	Ne4 -	- -	- -
Fritz Variation	... ...	... Nd4	c3 b5	Bf1! Nxd5	Ne4 -	- -	- -
Boden-Kieseritzky Gambit	Nc3 Nxe4	O-O Nxc3	dxc3 Qe7	Ng5 Nd8	- -	- -	- -
Giuoco Pianissimo Giuoco Piano The Giuoco Piano is a chess opening beginning with the moves:Common alternatives to 3...Bc5 include 3...Nf6 , 3...Be7 , or 3...d6 .-History:... , by transposition	d3 Bc5	- -	- -	- -	- -	- -	- -
3	... d5!?	exd5 Nxd5	- -	- -	- -	- -	- -
4	... Be7	- -	- -	- -	- -	- -	- -
5	d4 exd4	- -	- -	- -	- -	- -	- -
6	... ...	O-O Nxe4	Re1 d5	Bxd5 Qxd5	Nc3 -	- -	- -
Max Lange Attack Max Lange Attack The Max Lange Attack is a chess opening that can arise from many different opening lines, including the Two Knights Defense, Petroff's Defense, Scotch Gambit, Bishop's Opening, Center Game, and Giuoco Piano...	... ...	... Bc5	e5 d5	exf6 dxc4	Re1+ Be6	Ng5 Qd5	Nc3 Qf5
8	... ...	e5 d5	Bb5 Ne4	Nxd4 Bc5	- -	- -	- -
9	... ...	... Ne4	- -	- -	- -	- -	- -
10	... ...	... Ng4	- -	- -	- -	- -	- -

4.Ng5

Siegbert Tarrasch

Siegbert Tarrasch

Siegbert Tarrasch was one of the strongest chess players and most influential chess teachers of the late 19th century and early 20th century....

 called 4.Ng5 a "duffer's move" (ein richtiger Stümperzug) and Panov

Vasily Panov

Vasily Nikolayevich Panov was a Soviet chess player, author, and journalist. Winner of the Moscow City Championship in 1929, he also played in five USSR Chess Championships from 1935 to 1948. His greatest tournament victory was Kiev, 1938...

 called it "primitive", but this attack on f7 practically wins a pawn by force.
Despite Tarrasch's criticism, many players consider 4.Ng5 White's best chance for an advantage and it has been played by World Champions Wilhelm Steinitz

Wilhelm Steinitz

Wilhelm Steinitz was an Austrian and then American chess player and the first undisputed world chess champion from 1886 to 1894. From the 1870s onwards, commentators have debated whether Steinitz was effectively the champion earlier...

, Bobby Fischer

Bobby Fischer

Robert James "Bobby" Fischer was an American chess Grandmaster and the 11th World Chess Champion. He is widely considered one of the greatest chess players of all time. Fischer was also a best-selling chess author...

, Anatoly Karpov

Anatoly Karpov

Anatoly Yevgenyevich Karpov is a Russian chess grandmaster and former World Champion. He was the official world champion from 1975 to 1985 when he was defeated by Garry Kasparov. He played three matches against Kasparov for the title from 1986 to 1990, before becoming FIDE World Champion once...

, Garry Kasparov

Garry Kasparov

Garry Kimovich Kasparov is a Russian chess grandmaster, a former World Chess Champion, writer, political activist, and one of the greatest chess players of all time....

, and Viswanathan Anand

Viswanathan Anand

V. Anand or Anand Viswanathan, usually referred as Viswanathan Anand, is an Indian chess Grandmaster, the current World Chess Champion, and currently second highest rated player in the world....

.

Czech

Czech Republic

The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....

 problemist

Chess problem

A chess problem, also called a chess composition, is a puzzle set by somebody using chess pieces on a chess board, that presents the solver with a particular task to be achieved. For instance, a position might be given with the instruction that White is to move first, and checkmate Black in two...

 Karel Traxler

Karel Traxler

----Karel Traxler was a Czech chess master and composer of chess problems.He is best known for the hyper-aggressive variation named after him, the Traxler Variation in the Two Knights Defense, which was first shown in the following game against Reinisch, played in Hostouň in 1890:1.e4 e5 2.Nf3 Nc6...

 played 4...Bc5!? in Reinisch–Traxler, Prague

Prague

Prague is the capital and largest city of the Czech Republic. Situated in the north-west of the country on the Vltava river, the city is home to about 1.3 million people, while its metropolitan area is estimated to have a population of over 2.3 million...

 1896. Some decades later, several Pennsylvania chess amateurs, (mainly K. Williams) analyzed the variation and decided to name it after their hometown Wilkes-Barre, Pennsylvania

Wilkes-Barre, Pennsylvania

Wilkes-Barre is a city in the U.S. state of Pennsylvania, the county seat of Luzerne County. It is at the center of the Wyoming Valley area and is one of the principal cities in the Scranton/Wilkes-Barre metropolitan area, which had a population of 563,631 as of the 2010 Census...

, so today 4...Bc5 is known as both the Traxler Variation and (in the U.S.A. and the United Kingdom only) the Wilkes-Barre Variation.
This bold move ignores White's attack on f7 and leads to wild play where a number of long variations have been analyzed to a draw

Draw (chess)

In chess, a draw is when a game ends in a tie. It is one of the possible outcomes of a game, along with a win for White and a win for Black . Usually, in tournaments a draw is worth a half point to each player, while a win is worth one point to the victor and none to the loser.For the most part,...

 by perpetual check

Perpetual check

In the game of chess, perpetual check is a situation in which one player can force a draw by an unending series of checks. Such a situation typically arises when the player who is checking cannot deliver checkmate; while failing to continue the series of checks gives the opponent at least a chance...

.
White can play 5.d4, 5.Nxf7, or 5.Bxf7+.
After 5.d4 d5!, White's best is to go into an equal endgame after 6.dxc5 dxc4 7.Qxd8+. Other sixth moves have scored very badly for White.
The usual move used to be 5.Nxf7, but this 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. In the year 2000, this last move (which was already considered by Traxler himself) was credited as the 'refutation' of the Traxler variation, after an article in the New in Chess Yearbook series, featuring a cover diagram after White's seventh move. However, computer analysis subsequently showed that Black can probably force a draw after this move as well.
White's best try for an advantage is probably 5.Bxf7+ Ke7 6.Bb3, as this poses Black the most problems.
No grandmasters have regularly adopted the Wilkes-Barre as Black, but Alexander Beliavsky

Alexander Beliavsky

-External links:...

 and Alexei Shirov

Alexei Shirov

Alexei Dmitrievich Shirov is a Soviet-born Latvian chess grandmaster. He has consistently ranked among the world's top players since the early 1990s, and reached a ranking as high as number four in 1998...

 have played it occasionally even in top competition. No clear refutation is known.

More common is 4...d5 5.exd5. The recapture 5...Nxd5?! is very risky.
Pinkus

Albert Pinkus

Albert Sidney Pinkus was an American chess master and author. In 1943 and 1944, he published an analysis of the Two Knights Defense in Chess Review.-Chess career:...

 tried to bolster this move with analysis in 1943 and 1944 issues of Chess Review

Chess Review

Chess Review is a U.S. chess magazine that was published from January 1933 until October 1969 . Until April 1941 it was called The Chess Review. Published in New York, it began on a schedule of at least ten issues a year but later became a monthly...

,
but White gets a strong attack with either the safe Lolli

Giambattista Lolli

Giambattista Lolli was an Italian chess player. Lolli was one of the most important chess theoreticians of his time. He is most famous for his book Osservazioni teorico-pratiche sopra il giuoco degli scacchi , published 1763 in Bologna...

 Variation 6.d4! or the sacrificial Fried Liver (or Fegatello) Attack

Fried Liver Attack

The Fried Liver Attack, also called the Fegatello Attack , is a chess opening. This colourfully named opening is a variation of the Two Knights Defense in which White sacrifices a knight for a superficially impressive attack on Black's king...

6.Nxf7!? Kxf7 7.Qf3+ Ke6 8.Nc3.
These variations are usually considered too difficult for Black to defend over the board, but they are sometimes used in correspondence play.
Instead Black usually chooses to make the opening a gambit

Gambit

A gambit is a chess opening in which a player, most often White, sacrifices material, usually a pawn, with the hope of achieving a resulting advantageous position. Some well-known examples are the King's Gambit , Queen's Gambit , and Evans Gambit...

 by playing 5...Na5 (main line), 5...Nd4 or 5...b5.

After 5...Na5, Morphy

Paul Morphy

Paul Charles Morphy was an American chess player. He is considered to have been the greatest chess master of his era and an unofficial World Chess Champion. He was a chess prodigy...

 would play to hold the gambit pawn with 6.d3.
The Morphy Variation has not been popular, since it has long been known that Black obtains good chances for the pawn with 6...h6 7.Nf3 e4 8.Qe2 Nxc4 9.dxc4 Bc5. (Bronstein once tried the piece sacrifice 8.dxe4!? with success, but its soundness is doubtful.)
Instead, White usually plays 6.Bb5+, when play almost always continues 6...c6 7.dxc6 bxc6 8.Be2 h6.
(The move 8.Qf3?!, popular in the nineteenth century and revived by Bogoljubov in the twentieth, is still played occasionally, but Black obtains a strong attack after either 8...h6! or 8...Rb8.)
White then has a choice of retreats for the knight.
The usual move here is 9.Nf3, after which Black obtains some initiative after 9...e4 10.Ne5 Bd6 (this is considered to be the main line of the Two Knights Defense).
Steinitz favored 9.Nh3 instead, although it did not bring him success in his famous 1891 cable match against Chigorin.
The Steinitz Variation was mostly forgotten until Fischer revived it in the 1960s.
Nigel Short

Nigel Short

Nigel David Short MBE is an English chess grandmaster earning the title at the age of 19. Short is often regarded as the strongest English player of the 20th century as he was ranked third in the world, from January 1988 – July 1989 and in 1993, he challenged Garry Kasparov for the World Chess...

 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.

Black's alternatives to 5...Na5, the Fritz Variation 5...Nd4, and Ulvestad's Variation 5...b5, are related as they share a common subvariation.
American master Olav Ulvestad introduced 5...b5 in a 1941 article in Chess Review.
White has only one good reply.
Weak are 6.Bxb5 Qxd5 7.Bxc6 Qxc6 and 6.dxc6 bxc4 7.Nc3; the strongest move is considered the surprising 6.Bf1!, protecting g2 so White can answer 6...Qxd5? with 7.Nc3.
Black's best response is to 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.
German master Alexander Fritz

Alexander Fritz

Alexander Fritz was a German chess master.He tied for fifth/sixth with Wilfried Paulsen at Frankfurt 1878 , took 9th at Braunschweig 1880 Alexander Fritz (15 January 1857, Kirchlotheim - 22 April 1932, Alsfeld) was a German chess master.He tied for fifth/sixth with Wilfried Paulsen at Frankfurt...

 (1857–1932) suggested 5...Nd4 to Carl Schlechter

Carl Schlechter

Carl Schlechter was a leading Austrian chess master and theoretician at the turn of the 20th century. He is best known for drawing a World Chess Championship match with Emanuel Lasker.-Early life:...

, who wrote about the idea in a 1904 issue of Deutsche Schachzeitung

Deutsche Schachzeitung

Deutsche Schachzeitung was the first German chess magazine.Founded in 1846 by Ludwig Bledow under the title Schachzeitung der Berliner Schachgesellschaft, it took the name Deutsche Schachzeitung in 1872...

.
In 1907 Fritz himself wrote an article about his move in the Swedish

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 journal Tidskrift för Schack.
White's best reply is 6.c3, when the game often continues 6...b5 7.Bf1 Nxd5 8.Ne4 or 8.h4.

4.Nc3

The attempt to defend the pawn with 4.Nc3 does not work well since Black can take the pawn anyway and use a fork

Fork (chess)

In chess, a fork is a tactic that uses a single piece to attack multiple pieces at the same time. The attacker usually hopes to gain material by capturing one of the opponent's pieces. The defender often finds himself in a difficult position in which he cannot counter all threats. The attacking...

 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

Gambit

A gambit is a chess opening in which a player, most often White, sacrifices material, usually a pawn, with the hope of achieving a resulting advantageous position. Some well-known examples are the King's Gambit , Queen's Gambit , and Evans Gambit...

 the e-pawn with the Boden-Kieseritzky Gambit

Petrov's Defence

Petrov's Defence is a chess opening characterised by the following moves:Though this symmetrical response has a long history, it was first popularised by Alexander Petrov, a Russian chess player of the mid-19th century...

, 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

Blitz chess

Fast chess, also known as blitz chess, lightning chess, sudden death, speed chess, bullet chess and rapid chess, is a type of chess game in which each side is given less time to make their moves than under the normal tournament time controls of 60 to 180 minutes per player.-Overview:The different...

.

4.d3

The quiet move 4.d3 transposes into the Giuoco Pianissimo

Giuoco Piano

The Giuoco Piano is a chess opening beginning with the moves:Common alternatives to 3...Bc5 include 3...Nf6 , 3...Be7 , or 3...d6 .-History:...

 if Black responds 4...Bc5, but there are also independent variations after 4...Be7 or 4...h6.
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

Ruy Lopez

The Ruy Lopez, also called the Spanish Opening or Spanish Game, is a chess opening characterised by the moves:-History:The opening is named after the 16th century Spanish priest Ruy López de Segura, who made a systematic study of this and other openings in the 150-page book on chess Libro del...

 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

John Nunn

John Denis Martin Nunn is one of England's strongest chess players and once belonged to the world's top ten. He is also a three times world champion in chess problem solving, a chess writer and publisher, and a mathematician....

 and others.
Black can confound White's attempt to avoid tactical play with 4...d5!?.
This move is rarely played as opening theory does not approve, but Jan Piński suggests that it is better than is commonly believed.

4.d4

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, or obtain good chances with the complex Max Lange Attack

Max Lange Attack

The Max Lange Attack is a chess opening that can arise from many different opening lines, including the Two Knights Defense, Petroff's Defense, Scotch Gambit, Bishop's Opening, Center Game, and Giuoco Piano...

 after 5...Bc5 6.e5 d5.
The extensively analyzed Max Lange can also arise from the Giuoco Piano or Scotch Game.
White can choose to avoid these lines by playing 5.e5, a line often adopted by Sveshnikov

Evgeny Sveshnikov

Evgeny Ellinovich Sveshnikov is a Latvian, former Soviet International Grandmaster of chess, and a chess writer.-The player:...

.
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.

External links

• Harding, Tim (March 2001). The Kibitzer: Two Knights Defense, Part 1 (PDF
  Portable Document Format
  Portable Document Format is an open standard for document exchange. This file format, created by Adobe Systems in 1993, is used for representing documents in a manner independent of application software, hardware, and operating systems....
  
  ). Chesscafe.com.
• Harding, Tim (April 2001). The Kibitzer: Two Knights Defense, Part 2 (PDF
  Portable Document Format
  Portable Document Format is an open standard for document exchange. This file format, created by Adobe Systems in 1993, is used for representing documents in a manner independent of application software, hardware, and operating systems....
  
  ). Chesscafe.com.
• Harding, Tim (May 2001). The Kibitzer: Two Knights Defense, Part 3 (PDF
  Portable Document Format
  Portable Document Format is an open standard for document exchange. This file format, created by Adobe Systems in 1993, is used for representing documents in a manner independent of application software, hardware, and operating systems....
  
  ). Chesscafe.com.