Italian Game: Two Knights Defense, Polerio Defense
Italian Game: Two Knights Defense
Definition
The Two Knights Defense is a combative reply to the Italian Game that begins with the moves 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6. Instead of mirroring White’s bishop with 3…Bc5 (the Giuoco Piano), Black develops the king’s knight to f6, immediately attacking the e4-pawn and inviting sharp, tactical play. The opening is catalogued in ECO codes C55–C59.
Typical Move Order
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6
From here the game can branch into very different landscapes:
- 4. d3 – a quiet, strategic Italian setup (C55).
- 4. d4 exd4 5. e5 – the Max Lange–style center-punch (C56).
- 4. Ng5 – the ultra-tactical “Knight Attack” (C57–C59), leading to lines such as the Fried Liver Attack, the Polerio Defense, or the Traxler (Wilkes-Barre) Counter-attack.
Strategic Themes
- Immediate pressure on e4. Black hopes to force White into an early concession—either defending the pawn awkwardly or sacrificing it for activity.
- Rapid development & king safety. Because both sides often castle opposite wings (or delay castling entirely), piece activity can outweigh material considerations.
- Central tension. Breaks with …d5 (for Black) or d4 (for White) determine whether the position becomes an open slug-fest or a closed maneuvering battle.
Historical Significance
Traced to Gioachino Greco (17th century) and later analyzed by Giulio Cesare Polerio, the Two Knights Defense developed into one of the first “romantic” openings, celebrating sacrifices and mating attacks. Modern engines still show respect: with best play it remains entirely sound.
Illustrative Mini-Example
After 6.Nxf7 (the Fried Liver Attack), White wins a pawn and disrupts Black’s king, but Black can survive with accurate defense (…Ke6!, …c6, …Be7). Many scholastic players remember losing on move 10 here—proof of the opening’s instructional value.
Interesting Facts
- The famous Traxler Counter-attack (4…Bc5!?) deliberately ignores the threat on f7 and aims for an immediate assault on f2, showing how double-edged the Two Knights can become.
- World Champions such as Garry Kasparov and Magnus Carlsen have both used the defense as Black and as White in rapid chess to surprise opponents accustomed to quieter Italian lines.
Polerio Defense
Definition
The Polerio Defense is a principal branch of the Two Knights Defense arising after the forcing sequence 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5 Na5. Named for the Renaissance analyst Giulio Cesare Polerio (c. 1550–1610), the move 5…Na5 sidesteps the dreaded Fried Liver (5…Nxd5 6.Nxf7!), chases White’s bishop, and aims for long-term compensation through activity and the bishop pair.
Key Ideas for Both Sides
- Black avoids early material loss. By attacking White’s c4-bishop with 5…Na5, Black forces it off the a2–g8 diagonal, making the tactic Nxf7 much less potent.
- Piece activity & pawn structure. Black often accepts a damaged queenside pawn structure (…c6xb5) in return for rapid development and open lines for the bishops.
- White’s extra pawn or space? In many lines White emerges a pawn up but must weather Black’s initiative. Accurate defense and timely liquidation (e.g., d4 followed by c3 and d4-d5 breaks) are essential.
Sample Continuations
- 6. Bb5+ c6 7. dxc6 bxc6 8. Be2. White hangs on to the extra pawn; Black gains the bishop pair and a half-open b-file for counterplay.
- 6. Bb3 Nxb3 7. axb3. A calmer line in which Black trades bishop for knight, fractures White’s queenside, and later targets b2/b3 with …Bf5 or …Qxd5.
- 6. Be2 h6 7. Nf3 e4! A modern, dynamic setup leading to mutual chances and complicated middlegames.
Historical & Theoretical Notes
Although Polerio’s manuscripts date from the late 16th century, the variation’s strategic depth was appreciated only much later. In the 20th century it became a mainstay in the repertoires of technical endgame players such as Vasily Smyslov, who relished the pressure of the bishop pair. Today engines rate 5…Na5 as fully sound (≈ 0.00) and safer than 5…Nxd5.
Illustrative Game
Garry Kasparov – Veselin Topalov, Linares 1999 (rapid excerpt)
Kasparov’s energetic pawn sacrifice 12.d4!? invited chaos; Topalov accepted and eventually out-tacticked the former World Champion. Analysts hailed the game as proof that the Polerio can produce world-class fireworks.
Interesting Facts & Anecdotes
- In many amateur databases the entire 4.Ng5 line is still nick-named “Fried Liver,” yet elite practice overwhelmingly prefers the Polerio Defense to stay out of immediate trouble.
- Engines recommend the surprising retreat 5…Nd4!? (the Fritz Variation) as an even sharper alternative, but human grandmasters often stick to 5…Na5 to avoid forcing memorization of very concrete computer lines.
- Polerio’s original handwritten notebooks were rediscovered only in the early 20th century, confirming that many “modern” ideas were actually analyzed more than 400 years ago.