King's Indian: Four Pawns Attack, 5...O-O 6.Nf3
King's Indian Defense: Four Pawns Attack, 5...O-O 6.Nf3
Definition
The line arises after the moves 1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.f4 O-O 6.Nf3. It is a sub-variation of the Four Pawns Attack within the King’s Indian Defense (KID). White supports an expansive pawn center with f-pawn advance while calmly developing the knight to f3. Black castles immediately, deferring the traditional counter-blow …c5 or …e5 to the next move.
Move-order Context
The critical branching points are:
- After 5.f4, Black can choose 5…c5, 5…e5, or the flexible 5…O-O.
- White’s sixth move is normally 6.Nf3, 6.Be2, or 6.Nf3 exerts a small tempo-saving idea: the knight heads to d2 only after …c5xd4 if needed.
Strategic Themes
- White’s central space: With pawns on e4, d4, c4, and f4, White seizes the centre and restricts Black’s minor pieces.
- Black’s counterplay:
- …c5 combined with …Nc6 and …e5 breaks at d4/e4.
- Piece pressure on the long diagonal g7–a1 after …c5 opens the c-file.
- Stand-by sacrifice: …cxd4 followed by …e5!? can rip the centre before White finishes development.
- Development races: White often delays kingside castling, eyeing a possible g- or h-pawn storm, while Black tries to prove the centre is over-extended before that happens.
- Typical endings: If the centre stabilises, White’s space may give enduring pressure; if it collapses, Black’s bishops dominate open diagonals.
Historical Significance
The Four Pawns Attack was fashionable in the 1920s–1930s thanks to Aaron Nimzowitsch and Rudolf Spielmann. The 5…O-O 6.Nf3 move order became popular later, when defenders such as Isaac Boleslavsky and Efim Geller discovered more resilient counter-attacks compared with the older, direct 5…c5. In modern times, elite grandmasters (e.g., Teimour Radjabov, Hikaru Nakamura) still employ it as a surprise weapon.
Illustrative Example
The following miniature shows both sides’ plans in action:
Black’s delayed break …e6 and …dxe5 undermines the pawn phalanx; White obtains attacking chances but the centre starts to dissolve—illustrating the double-edged nature of the line.
Typical Plans After 6.Nf3
- For White
- Advance e4-e5 to gain space and cramp Black’s pieces.
- Prepare kingside-piece buildup: Be2, 0-0, Qe1–h4, Bh6 ideas.
- If Black breaks with …c5, consider d4-d5 and sometimes e4-e5 + f4-f5.
- For Black
- Immediate 6…c5 or 6…Na6 heading for …c5.
- Timely …e5 after …c5xd4 to hit e4.
- Piece pressure on the d4-pawn; manoeuvres like …Nbd7-b6-c4.
Interesting Facts & Anecdotes
- The Four Pawns Attack horrified classical players—José Raúl Capablanca reportedly called it “unsound,” yet modern engines rate it fully playable.
- Because the pawn wedge resembles a spear, Soviet trainers nick-named the White center in this line “the trident.”
- Grandmaster Mikhail Tal once quipped that facing the Four Pawns Attack felt like trying to “fish in hurricane-strength waves”—either you catch the centre at once or you drown.
When to Choose It
5…O-O 6.Nf3 is a sound yet combative way for Black to meet the Four Pawns Attack, ideal for players who relish dynamic counterplay and are comfortable with unbalanced pawn structures. For White, opting for 6.Nf3 keeps pieces on the board and often leads to rich middlegames rather than forcing early sacrifices.