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| Moves | 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 | ||||||||||||||||||||||||||||||||||||||||||||
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| ECO | C55–C59 | ||||||||||||||||||||||||||||||||||||||||||||
| Origin | Late 16th century | ||||||||||||||||||||||||||||||||||||||||||||
| Parent | Italian Game | ||||||||||||||||||||||||||||||||||||||||||||
| Synonym(s) | Prussian Defense[1] | ||||||||||||||||||||||||||||||||||||||||||||
TheTwo Knights Defense (also called thePrussian Defense) is achess opening that begins with the moves:
First recorded byGiulio Cesare Polerio[2] (c. 1550 – c. 1610) in the late 16th century, this line of theItalian Game was extensively developed in the 19th century. Black's third move is a more aggressive defense than theGiuoco Piano (3...Bc5). Black allows White to attack his f7-pawn 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 theinitiative. The complications are such thatDavid Bronstein suggested that the term "defense" does not fit, and that the name "Chigorin Counterattack" would be more appropriate.[3] The Two Knights has been adopted as Black by many aggressive players includingMikhail Chigorin andPaul Keres, andworld championsMikhail Tal andBoris Spassky. In moderngrandmaster play, 3.Bc4 is less common than3.Bb5, and the more solid 3...Bc5 is the most frequent reply, so the Two Knights Defense is infrequently seen. It remains popular with amateur players. The theory of this opening has been explored extensively incorrespondence chess by players such asHans Berliner andYakov Estrin.
German masterSiegbert Tarrasch called 4.Ng5 "a real duffer's move" (ein richtiger Stümperzug) and Soviet opening theoristVasily Panov called it "primitive", but this attack on f7 practically wins a pawn byforce. Despite Tarrasch's criticism, 4.Ng5 has remained a popular choice for White at all levels.
After 4...d5 White has little option but to play 5.exd5, since both the bishop and e4-pawn are attacked. Then Black usually plays 5...Na5 but there are other options:
| 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 | ||
After 5...Na5, the Polerio Defense,[7][8]Paul Morphy would play to hold the gambit pawn with 6.d3, theKieseritzky Attack (or Morphy Variation), which 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.[3][9])
Instead, White usually plays 6.Bb5+, when play usually continues 6...c6 (6...Bd7 is also possible[5]) 7.dxc6 bxc6 8.Be2 h6. (The move 8.Qf3, popular in the nineteenth century and revived byEfim Bogoljubow in the twentieth, can be played instead; Black may reply with 8...h6, 8...Rb8, or 8...Be7.) 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 (see diagram). This is the Knorre Variation, and is considered to be the main line of the Two Knights Defense. After ten moves, White has developed only two pieces against Black's three pieces and pawns, but has an extra pawn as well as a better pawn structure. Both 11.d4 and 11.f4 have been tried here with no definitive conclusion. 10...Bc5 is a viable alternative for Black, as is 10...Qc7 (the Goring Variation).[10]
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 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. In addition to the moves 8.Be2 and 8.Qf3, the move 8.Bd3 is a valid alternative that has apparently become fashionable in recent years.[5]
This bold move ignores White's attack on f7 and leads to wild play. CzechproblemistKarel Traxler played it against Reinisch inPrague in 1890.[11] Later it was named afterWilkes-Barre, Pennsylvania byFrank Marshall, who claimed to be first to analyze and publish it,[12] so today 4...Bc5 is known as both the Traxler Variation and (in the United States and the United Kingdom[13] only) the Wilkes-Barre Variation.
White can play 5.d4, 5.Nxf7, or 5.Bxf7+:
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.[14] (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:
White can choose todevelop rapidly with 4.d4 exd4 5.0-0. Now Black canequalize simply by eliminating White's last center pawn with 5...Nxe4, after which White regains thematerial with 6.Re1 d5 7.Bxd5 Qxd5 8.Nc3, but Black has a comfortable position after 8...Qa5 or 8...Qh5.
The wildNakhmanson 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.[16]
Alternatively, Black can enter the extensively analyzedMax 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 bySveshnikov. After 5.e5, either 5...Ne4 or 5...Ng4 is aplayable reply, but most common and natural is 5...d5 6.Bb5 Ne4 7.Nxd4 Bc5, withsharp play. The tricky 5.Ng5?! is best met by 5...d5! 6.exd5 Qe7+!
The quiet move 4.d3, the Modern Bishop's Opening,[17] transposes into theGiuoco Pianissimo 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 theRuy 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 byJohn Nunn and others.
The attempt to defend the pawn with 4.Nc3 does not work well since Black can take the pawn anyway and use afork trick to regain the piece, 4.Nc3?! Nxe4! 5.Nxe4 d5. The try 5.Bxf7+? does not help, as Black has thebishop pair and a better position after 5...Kxf7 6.Nxe4 d5. Instead, 4.Nc3 is usually played with the intent togambit the e-pawn with theBoden–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 inblitz chess.
| 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 | ||
| 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 | ||
| 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 | ||
| 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 | ||
White must respond to the attack on the e-pawn. (For explanation of notation, seechess opening theory table.)
| 4 | 5 | 6 | 7 | 8 | 9 | 10 | |||
|---|---|---|---|---|---|---|---|---|---|
| Traxler or Wilkes-Barre Variation | Ng5 Bc5!? | Bxf7+! Ke7 | Bb3! - | - - | - - | - - | - - | ||
| Lolli Attack | ... d5 | exd5 Nxd5?! | d4! - | - - | - - | - - | - - | ||
| Fried Liver Attack | ... ... | ... ... | Nxf7!? Kxf7 | Qf3+ Ke6 | Nc3 - | - - | - - | ||
| Kieseritzky Attack | ... ... | ... 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 - | - - | - - | ||
| ... Nxe4?! | Bxf7+! Ke7 | d4! d5 | Nc3! Nxc3 | bxc3 Qd6 | a4! Kd8 | Bg8! - | |||
| Boden–Kieseritzky Gambit | Nc3 Nxe4 | 0-0 Nxc3 | dxc3 Qe7 | Ng5 Nd8 | - - | - - | - - | ||
| Modern Bishop's Opening | d3 Be7 | - - | - - | - - | - - | - - | - - | ||
| ... h6 | - - | - - | - - | - - | - - | - - | |||
| ... d5!? | exd5 Nxd5 | - - | - - | - - | - - | - - | |||
| Giuoco Pianissimo(by transposition) | ... Bc5 | - - | - - | - - | - - | - - | - - | ||
| d4 exd4 | e5 d5 | Bb5 Ne4 | Nxd4 Bc5 | - - | - - | - - | |||
| ... ... | 0-0 Nxe4 | Re1 d5 | Bxd5 Qxd5 | Nc3 - | - - | - - | |||
| Max Lange Attack | ... ... | ... Bc5 | e5 d5 | exf6 dxc4 | Re1+ Be6 | Ng5 Qd5 | Nc3 Qf5 | ||
| ... ... | e5 d5 | Bb5 Ne4 | Nxd4 Bc5 | - - | - - | - - | |||
| ... ... | ... Ne4 | - - | - - | - - | - - | - - | |||
| ... ... | ... Ng4 | - - | - - | - - | - - | - - |
Bibliography
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