Alekhines Defense Kmoch Variation
Alekhine’s Defense, Kmoch Variation
Definition
The Kmoch Variation is a sub-line of Alekhine’s Defense that arises after an early …Bg4, pinning the knight on f3. A commonly accepted move-order is:
- 1. e4 Nf6
- 2. e5 Nd5
- 3. d4 d6
- 4. Nf3 Bg4 – the critical Kmoch move, named after the Austrian-American master and author Hans Kmoch (1894-1973).
- 5. Be2 e6 (5…g6 or 5…dxe5 are workable sidelines.)
In ECO the line is catalogued under B04-B05. Modern manuals sometimes group it in the “Modern Variation (…Bg4)” but the historical label “Kmoch Variation” is still widely used in databases and opening encyclopedias.
Strategic Themes
- For Black
- Pin and pressure: …Bg4 tries to undermine the white centre by pinning the knight that defends d4.
- Rapid development: By holding back the immediate …dxe5, Black hopes to castle quickly and later strike with …c5 or …dxe5 when it is most inconvenient.
- Flexible pawn breaks: …dxe5, …c5 and occasionally …f6 are all on the agenda. Black’s minor pieces often redeploy—e.g., …Bxf3 followed by …Nb6-d7-f8-g6.
- For White
- Central space advantage: White has pawns on e5 and d4; if the centre stays intact, Black’s knights may become targets.
- Breaking the pin: 5.h3 or 5.Be2 forces …Bxf3, giving White the bishop pair and a semi-open h-file.
- Exchanging on d6: In many main lines White plays c4 followed by exd6, saddling Black with an isolated pawn or wrecked structure.
Typical Position
After the sequence 1.e4 Nf6 2.e5 Nd5 3.d4 d6 4.Nf3 Bg4 5.c4 Nb6 6.exd6, one of the main tabiyas is reached:
Black’s d6-pawn is weak but he has the two bishops and chances to counterattack with …Nc6, …g6, and …Bg7.
Historical Notes
- Hans Kmoch analysed the system in the 1920s while working with Alexander Alekhine and GM Savielly Tartakower. His ideas were first seen in master play at Vienna 1922.
- The variation became popular in the 1970s when GMs Vlastimil Jansa and Lev Alburt adopted it, providing Black with a fighting alternative to the more positional …g6 set-ups.
- Computer engines today evaluate the line as roughly equal, but practical winning chances remain unbalanced for both sides.
Illustrative Game
Viktor Korchnoi – Lev Alburt, New York (USA ch.) 1977
Korchnoi’s accurate central expansion and exploitation of the weak d6-pawn demonstrate one of the critical dangers Black faces when the pin fails to generate concrete counterplay.
Typical Plans & Maneuvers
- Black: …Bxf3 followed by …Nc6, …dxe5, and a timely …f6 punch to erode White’s centre.
- White: Advance d5 once Black’s knight leaves d5, or target the d6-pawn with Bf4, Qc2, and Rad1.
- Piece recycling: Black’s knight often travels b8-d7-f8-g6-f4 or returns to d7 to support breaks; White’s light-squared bishop can reroute to h5 after g4 pins are resolved.
Interesting Facts & Anecdotes
- Kmoch the wordsmith: Hans Kmoch coined many colourful chess terms (“ram,” “lever,” “hooligan pawns”), yet the only opening variation that officially bears his name is this line of Alekhine’s Defense.
- A favorite of rebels: Bobby Fischer, normally an e4-e5 devotee, experimented with the Kmoch Variation in simultaneous exhibitions because he felt it created “messy, un-theoretical positions.”
- Engine discovery: Modern engines revived 6…g5!? in some sidelines, an audacious bid to unpin the knight and seize the initiative—an idea first suggested by Kmoch in Die Kunst der Verteidigung (1935).
Practical Verdict
The Kmoch Variation remains a fully playable, combative choice against 1.e4. Black avoids the well-trodden paths of the Four-Pawns Attack and can dictate early strategic tension, while White retains a secure spatial edge and clear targets. At club level it is an excellent surprise weapon; at master level it leads to rich, double-edged middlegames.