The Bayonet Attack and 9...a5: The Strategic Split Inside the King's Indian Defence

The game ended on move forty-one. No combination was sharp enough to lift a crowd out of its seats, no sacrifice made the evening bulletin. Black won by trading along the open file, keeping the pawn structure intact, and pushing a pawn through on the queenside while White still believed the position was balanced. White stood up, wrote move 23 on the scoresheet, and said nothing to anyone. I was sitting a few rows away, and I understood I had just watched the hardest thing in chess to sell: a good game with nothing to tell. The 2026 women's chess season closed with a fair number of games like that. At the level of theory, that game belongs to an old branch. The King's Indian Defence, Mar del Plata variation, with the familiar move order: 1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Nf3 0-0 6.Be2 e5 7.0-0 Nc6 8.d5 Ne7. From there White has several directions, and 9.b4 — the Bayonet Attack — has been the most fashionable for roughly a decade. White opens the queenside, pushes the pawn to b4, prepares b5 and c5, and turns the game into two counter-running races. ECO places the whole family around E97–E99. Black's orthodox answer is 9...Nh5. The knight goes to the rim, the game is forced onto a concrete track, and one off-beat move around move 15 can erase an entire preparation. At the top level the Bayonet Attack works, in other words, as a memory test. There is another road, and in 2026 it was discussed far more often: 9...a5. Technically the ninth move does something very simple — it asks the b4-pawn how long it intends to stay. Black does not fight for the centre by opening the kingside as with 9...Nh5. Black keeps the closed pawn structure, concedes White more space on the queenside, and in exchange gets a clear target and a position with few windows to be broken through. White still holds the space advantage with the c4–d5 chain, but that advantage only counts if White finds a concrete plan: b5 to open the queenside, or the knight back to d2 followed by c5. Play slowly, and the b4-pawn becomes a target while Black gets the time to play ...f5, ...g5, ...f4 — the moves every King's Indian player wants. One thing needs saying plainly: 9...a5 is not new. It is a known sideline, seen in scattered top-level games, but it has never displaced 9...Nh5 in the reference literature. The novelty, such as it is, lies in the pitch: an exit for players who want out of memorisation culture, accepting a balanced position in exchange for fewer forcing lines. Training material circulating in 2026 pushed exactly that point — equal chances, few concrete lines, and a Black player who needs to understand the position rather than recall a sequence. To a young Vietnamese player, that pitch sounds reasonable. Academies here still tend to measure progress by the number of lines a student can recite, and a road promising "play by understanding" has obvious appeal. Appeal, though, is not the same as a lower cost. When the cheering stops, I hear the true breathing of a game. 9...a5 produces games where the mistake is not one move but twenty even moves, each a little off. That is the hardest kind of risk to notice, and the hardest to fix. The largest blind spot in the word "antidote" is this: 9...a5 is public. A prepared White player has more options against it, not fewer. The real advantage of the branch comes from changing the character of the game, not from a new move. And character can be read in advance. Nor does "fewer lines" mean "less work". It shifts the burden from memory to judgement, and for most club players judgement is harder to train. Someone practising three evenings a week can memorise fifteen moves of a forcing line; to play forty moves correctly in a closed position they need something no book sells. Strategy is like people: you have to know who you are before you try to be someone else. 2026 shows the larger picture. At the Candidates Tournament in London, safe play and low theoretical risk dominated, while the King's Indian survived at the top level as a surprise weapon rather than a daily choice. A sideline does not reverse that trend. Elsewhere in the year, Hou Yifan regained the women's world title in Taizhou, beating Anna Ushenina 5½–2½ in the eight-game match played in September. The difference between the two players lay in preparation, and in the ability to hold rhythm when a game drifts into territory nobody wants. In chess I do not watch the screen; I watch how they keep calm while they are losing. Vietnam's generation of women players — Nguyễn Thị Thanh An, Phạm Lê Thảo Nguyên, Hoàng Thị Bảo Trâm — opened the road for a younger group with more stylistic choices. Lines like 9...a5 widen that set. The value of the argument about the ninth move is not in who is right. It is that a sixteen-year-old can now say: I choose this position because it fits the way I think.