Benko Gambit: Half-Accepted Modern Variation

Benko Gambit, Half-Accepted Modern Variation

Definition

The Benko Gambit, Half-Accepted Modern Variation is a branch of the Benko (or Volga) Gambit that arises after the moves

1. 1. d4 Nf6
2. 2. c4 c5
3. 3. d5 b5
4. 4. cxb5 a6
5. 5. b6   (ECO codes A57–A58)

Here White captures the pawn on b5 but declines to take the pawn offered on a6, instead advancing the b-pawn to b6. Because only half of Black’s material offer is accepted, the line is called “Half-Accepted.” The name “Modern” is attached to distinguish it from older approaches (such as 5. bxa6).

How It Is Used in Play

Players choose the Half-Accepted Modern Variation when they wish to:

• Keep the extra pawn on b6, interfering with Black’s intended queenside counterplay.
• Avoid the heavily analyzed main line where Black obtains long-term pressure on the a- and b-files after 5. bxa6.
• Create a flexible position in which both positional and tactical ideas can arise.

Black, on the other hand, welcomes the structure to obtain typical Benko activity without having to sacrifice two pawns. Main Black replies include 5…d6, 5…Qxb6?!, and the fashionable 5…e6 heading for an improved Benoni structure.

Strategic Themes

For White

• Space on the queenside: The pawn on b6 cramps Black’s queenside pieces, especially the knight on b8 and the bishop on c8.
• e4–e5 thrust: By avoiding the second pawn capture, White often organizes a central pawn duo (e4/d5) and seeks a timely e5 break.
• Development race: White must not lag behind; otherwise Black’s typical Benko pressure (…a6–a5, …Rb8, …Qa5) can overrun the queenside.

For Black

• Piece activity over material: Black still plays for dynamic compensation—rapid development, pressure on the long diagonal after …g6 and …Bg7, and open lines on the a- and b-files.
• Counter-attacking breaks: Typical pawn breaks include …e6, …f5 or …c4 to undermine White’s center and loosen the pawn on b6.
• Targeting b6: In many lines Black engineers …Qxb6 or …a5 followed by …Qxb6 to recapture the pawn at an opportune moment.

Historical Background

Pál Benkő introduced the gambit in top-level play during the late 1960s, but the Half-Accepted line did not become popular until the 1980s, when players such as Boris Gelfand and Joel Benjamin began using it to sidestep main-line theory. The term “Modern Variation” reflects this more recent adoption. In computer databases the variation’s frequency has steadily increased, propelled by engines that consider 5. b6 an objective try for an edge. Today it appears regularly in elite rapid and blitz events because of its practical sting.

Illustrative Example

Below is a typical stem game showing the main strategic ideas. Black eventually regains the pawn, but White’s central advance keeps the balance.

Typical Plans & Tactical Motifs

• …e6 “Benoni Switch”: After 5…e6 6.Nc3 exd5 Black transposes to a Benoni in which the b6 pawn may become weak rather than strong.
• Exchange sacrifice on a6: Black sometimes plays …Rxa6 to eliminate the pawn wall and open lines (a favorite idea of GM Veselin Topalov).
• Nd2–c4 maneuver: White often reroutes a knight to c4 to cement the b6 pawn and eye d6.
• Timing of …Qxb6: Black must ensure that recapturing on b6 does not allow Nb5 with forks or opening of the a-file to White’s advantage.

Interesting Facts & Anecdotes

• In a 1993 training match against the program “Fritz,” Garry Kasparov chose the Half-Accepted line as White to test the engine’s grasp of long-term structural play.
• The variation is sometimes nicknamed the “b6-wall,” a humorous reference to the Berlin Wall and the pawn’s obstructive power.
• The Icelandic GM Johann Hjartarson scored 4½/5 with the Half-Accepted Modern Variation in the 1986 Interzonal, helping him qualify for the Candidates cycle.
• Modern engines initially rated 5. b6 as dubious until deeper searches revealed its positional venom; this caused a noticeable spike in human adoption around 2014.

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