Italian Game: Two Knights Defense, Polerio, Bogoljubow

Italian Game: Two Knights Defense

Definition

The Two Knights Defense is a branch of the Italian Game that begins with the moves 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6. Both sides develop their kingside knights rapidly, contesting the centre and preparing to castle. The opening is renowned for its sharp, tactical possibilities and has been a favourite of attacking players since the 19^th century.

Typical Move-Order

The basic tabiya is reached after:

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

From this point, White chooses among several fourth-move options:

4. Ng5 – the ultra-aggressive Knight Attack, leading toward the Polerio Defense and the famous Fried Liver motifs.
4. d4 – the Modern or Scotch Gambit approach, striking the centre immediately.
4. Nc3, 4. d3 or 4. Qe2 – quieter systems aiming for a long strategic battle.

Strategic Themes

Central Tension: Black allows White a temporary spatial advantage in return for rapid piece play.
Open e- and f-files: Both sides often castle kingside, after which the semi-open files can become highways for rooks and tactics.
Tactical Warfare: Sacrifices on f7, d5 or c6 are common. Accurate calculation is indispensable.
Pawn Structure: Black must decide whether to hold the e-pawn with …d6 or counter-attack with …d5.

Historical Significance

First analysed in the Renaissance, the line appears in the notebooks of Giulio Cesare Polerio (c. 1550 – 1610). Paul Morphy, Adolf Anderssen and later Bobby Fischer all contributed memorable games. In modern elite play, Magnus Carlsen, Fabiano Caruana and Ding Liren have revived the opening to avoid the deep theoretical jungles of the Ruy López.

Illustrative Mini-Game

The diagram (after 7…bxc6) showcases the rich imbalance typical of the Two Knights: Black is a pawn down but enjoys the bishop pair and active pieces, while White must handle threats on the a5-e1 diagonal.

Interesting Facts

Because the opening can transpose to the King’s Gambit Declined or even the Scotch, encyclopaedias classify it under a multitude of ECO codes (C55–C59).
Computer engines rate the Two Knights as fully sound for Black, overturning earlier 20^th-century scepticism.
In the 1997 Kasparov vs Deep Blue match, the world champion employed the quieter 4.d3 system to dodge the machine’s deep tactical preparation.

Polerio Defense (in the Two Knights)

Definition

The Polerio Defense is the principal response to White’s Knight Attack in the Two Knights Defense. It arises after 4. Ng5 d5 5. exd5 Na5, when Black sidesteps the notorious Fried Liver Attack (5…Nxd5?!) and immediately attacks the bishop on c4. The line is named for Italian theoretician Giulio Cesare Polerio, whose 16^th-century manuscripts already recommended …Na5.

Full Move-Sequence

1. e4 e5
2. Nf3 Nc6
3. Bc4 Nf6
4. Ng5 d5
5. exd5 Na5 (Polerio Defense)

Strategic Objectives

Safety First: By forcing the c4-bishop to move, Black prevents the immediate fork tactic Nxf7, saving the f7-pawn.
Active Piece Play: Black willingly concedes the d5-pawn to gain time and open lines for the bishops.
Bishop Pair vs. Material: After 6. Bb5+ c6 7. dxc6 bxc6, Black is a pawn down but has mobile pawn majorities and long-range bishops.
Long-Term Compensation: The a-knight can reroute via b7-d6, supporting breaks with …e4.

Key Continuations

6. Bb5+ (Main Line) 6…c6 7. dxc6 bxc6 8. Qf3 or 8. Be2 – leads toward the Bogoljubow Variation.
6. d6 (Lolli Attack) – an ultra-sharp try where White sacrifices a piece on f7.
6. Be2 – a quieter positional attempt aiming to cash in the extra pawn later.

Historical & Practical Value

Although sometimes labelled “risky,” the Polerio Defense has withstood centuries of analysis. Modern correspondence and engine games confirm its soundness. Grandmasters such as Garry Kasparov, Levon Aronian and Hikaru Nakamura have all employed …Na5 in serious competition.

Famous Example

Morphy – Thompson, New York 1859 featured the classic line 6. Bb5+ c6 7. dxc6 bxc6 8. Be2 h6 9. Nf3 e4, a model demonstration of Black’s dynamic potential.

Trivia

The alternative name “Knight Attack” refers to White’s 4.Ng5, not to Black’s …Na5.
Old books occasionally called 5…Na5 the “Cordel Defense,” but modern nomenclature honours Polerio instead.

Bogoljubow Variation (of the Polerio Defense)

Definition

The Bogoljubow Variation is a critical branch beginning after the further moves 6. Bb5+ c6 7. dxc6 bxc6 8. Be2 h6. It is named for two-time World Championship challenger Efim Bogoljubow, who championed the line in the 1920s and 30s. Black spends a tempo with …h6 to chase the intrusive knight, intending …e4 and rapid central expansion.

Move-Order in Context

1. e4 e5
2. Nf3 Nc6
3. Bc4 Nf6
4. Ng5 d5
5. exd5 Na5
6. Bb5+ c6
7. dxc6 bxc6
8. Be2 h6 (Bogoljubow Variation)

Strategic Hallmarks

Pawn Down, Initiative Up: Black’s extra tempo with …h6 forces the knight back, paving the way for …e4 to gain more space.
Central Roller: Typical plan – …e4, …Bd6, …0-0, and sometimes …Re8 and …Qe7, mobilising the e- and f-pawns.
King Safety: By preventing Nxf7+, Black ensures the king can castle safely and use the semi-open f-file later.
Piece Coordination: The a5-knight often heads to b7-d6, controlling key light squares around e4 and f5.

Model Game

After 12…O-O Black has regained the pawn and holds the initiative; Bogoljubow demonstrated this plan in several exhibition games in 1926–27.

Historical Notes

Bogoljubow first employed the variation in Karlsbad 1923. His success inspired further investigation by Spielmann, Najdorf and later Ulf Andersson. Modern engines still consider the line fully playable, giving roughly equal chances with best play.

Tips for Practitioners

Memorise the forcing tactical motifs on f2/f7; one slip can be fatal.
After 8…h6 9.Nf3 e4 10.Ne5, Black should know the manoeuvre …Bd6, …0-0 and sometimes …Qc7 to target h2.
White can choose 9.Nh3 or 9.Nh3 g5!? to mix the game further – be prepared for both.

Did You Know?

The line was briefly called the “Beatty Variation” in North American literature after Canadian master C.F. Beatty, who analysed it independently.
Bogoljubow himself famously quipped, “When I am White I win because I am White; when I am Black I win because I am Bogoljubow!” – a spirit that suits this ambitious pawn-sac line.