King’s Indian: Mar del Plata & Bayonet Attack 9...a5 10.bxa5

King’s Indian Defence: Mar del Plata Variation

Definition

The Mar del Plata Variation is a fiercely sharp branch of the Classical System of the King’s Indian Defence (KID). The characteristic move-order runs:

1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. Nf3 O-O 6. Be2 e5 7. O-O Nc6 8. d5 Ne7 9. Ne1 (or 9.Nd2) c6 10. Be3 cxd5 11. cxd5 Nd7.

Meaning & Key Ideas

• White gains space on the queenside with the pawn chain d4–d5–c4, while Black plans a thematic pawn-storm with … f7-f5 and often …g6-g5–g4 against White’s king.
• The resulting positions feature opposite-wing attacks where time is the most valuable commodity: whoever lands a decisive blow first usually wins.

Strategic Significance

King-side Race. Black’s pawn storm ( …f5, …g5, …g4) aims to open files against the white monarch on g1.
Queenside Expansion. White counters with b2-b4-b5 and c4-c5, or by sacrificing on c5 to break through.
Minor-piece Battles. The “good” and “bad” bishops of the KID (Black’s g7-bishop vs. Black’s c8-bishop) determine the long-term imbalances.

Historical Note

The line is named after the 1953 Mar del Plata tournament in Argentina where several dramatic games (most notably Najdorf – Gligorić) popularised this system. Svetozar Gligorić became one of its leading early practitioners, and Garry Kasparov later developed many modern improvements.

Illustrative Game

Najdorf – Gligorić, Mar del Plata 1953

Interesting Facts

Engine assessments often swing wildly: what looks lost can suddenly be winning several moves later.
In 1997 Kasparov used the Mar del Plata in both of his wins against the IBM computer “Deep Blue,” highlighting its practical brutality.

King’s Indian Defence: Bayonet Attack

Definition

The Bayonet Attack arises after the moves

1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. Nf3 O-O 6. Be2 e5 7. O-O Nc6 8. d5 Ne7 9. b4!

The pawn on b4 thrusts like a “bayonet” into Black’s position, seizing space on the queenside and fixing the c5-square as a future outpost for White’s pieces.

Typical Plans

White:
- b4-b5 to undermine c6 and open the b-file.
- c4-c5, often after preparatory moves, to gain more space.
- Knight manoeuvres Nf3-d2-c4/e3 to reinforce queenside play.
Black:
- Immediate counter-strike 9…a5 (main line) or the slower 9…Nh5.
- Usual KID pawn storm …f5, …g5, …g4 if allowed.
- Piece sacrifice ideas on e4 or a4 aimed at disrupting White’s structure.

Historical & Modern Relevance

Introduced into top practice in the late 1980s and popularised by GMs Mikhail Gurevich and Vladimir Kramnik, the Bayonet gave White a fresh, concrete way to question Black’s entire Classical KID setup. It remains one of the most respected tries for an edge against the defence.

Notable Game

Kramnik – Gelfand, Tilburg 1992

Trivia

The name “Bayonet” was coined by English GM Jonathan Speelman.
Engines originally disliked 9.b4 for White, but modern neural nets often give it a small plus, reflecting improved understanding of space advantage.

King’s Indian Defence: 9…a5 10.bxa5 Line

Definition

Within the Bayonet Attack, Black’s most direct response is the immediate pawn break 9…a5. After the capture 10.bxa5, the game enters a specific sub-variation where material equality is kept but the pawn structure becomes asymmetrical:

1. d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 O-O 6.Be2 e5 7.O-O Nc6 8.d5 Ne7 9.b4 a5 10.bxa5.

Strategic Themes

Open a-File. Both sides gain access to the a-file; control over a1–a8 becomes a long-term asset.
c6 Weakness. The missing Black a-pawn means that c6 is harder to defend once White breaks with b4-b5 or c4-c5.
Minor-Piece Activity. White often reroutes a knight to b5 or c4, while Black uses the a8-rook and queen to exert pressure on e4 and the a-file.

Typical Continuations

After 10…Nh5 11.g3 f5, play usually sharpens around the e4-square and kingside. Another tabiya is

10…Nd7 11.Nd2 f5 12.a4 with balanced chances.

Example Mini-Game

Adams – Topalov, Dortmund 1998

Interesting Nuggets

Engines now suggest the subtle move 10…Nh5!?, heading for f4, as the most resilient reply to 10.bxa5.
Despite appearing symmetrical, this line often transposes into razor-sharp positions reminiscent of the Mar del Plata pawn-storms—proving once again that structure alone does not guarantee calm play in the King’s Indian.