The 9...a5 Move Against the Bayonet Attack: A Strategic Detour in the King's Indian Defense

In my small office in Binh Duong, I reopened a familiar game. After eight moves, the King's Indian Defense appeared exactly as it has for more than half a century: 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. The center is locked. The two wings face each other across a silent valley. Then White pushes 9.b4, the Bayonet Attack. That move is not loud, but it is the biggest question the Mar del Plata system has posed to Black for decades. White drills a thrust down the queenside, opens the way for the b and c pawns, and forces Black to answer before building the kingside counterattack. For years, the orthodox answer was 9...Nh5. Then an opening DVD appeared, proposing a different path: 9...a5.

That DVD names no specific player. It simply presents an idea, a store of moves for the player holding the Black pieces. And it is precisely how it presents them that made me stop and sit down. This is the kind of product that has long existed in the chess world: an opening course packaged in the ChessBase style, sold to amateur players who want to build a system of their own. It does not promise a win; it promises a way of thinking.

To understand why 9...a5 deserves discussion, it must be placed next to 9...Nh5. Mar del Plata is the sharpest variation of the King's Indian Defense, where Black accepts ceding space in the center only to demolish the kingside with a pawn storm. The name Mar del Plata comes from the 2026 tournament held in the Argentine city of the same name, where the first games of this system left a deep mark on opening theory. Black's plan sounds simple: push ...f5, ...g5, ...h5, bring the rook to f6 and then h6, and tear open White's kingside. But that plan needs time, and White will not sit still.

The Bayonet Attack 9.b4 is exactly how White buys time: threatening b5 to drive away the c6 knight, then c5 to drill into the center, turning the queenside into the main front. White's idea is clear: if Black spends too much time starting the kingside, White will open the queenside first. This is a race between two storms, and the winner is the one who arrives a tempo earlier.

In that confrontation, 9...Nh5 is a forcing move. It opens the kingside, giving Black ...Nf4 or ...f5 immediately, but it also opens the way for White to calculate concretely. This is ground that computers have plowed over: thousands of games, hundreds of branches, every move verifiable by Stockfish or Leela. In other words, 9...Nh5 is a battle both sides must memorize, and whoever forgets a move pays for it.

9...a5 takes the opposite road. It does not open the kingside, it does not force White to calculate at once. It quietly controls the b4 square, slows White's thrust, and preserves the structure. Black accepts a long game, where the outcome comes not from a combination but from the accumulation of small advantages. This is the thinking of the positional player, who believes understanding matters more than memorization.

In theoretical terms, 9...a5 is not a new move. It has appeared in games and books for a long time; it has simply always stood in the second row, behind 9...Nh5. The DVD did not invent it, but repackaged it as a main choice, with an appealing promise: this is the way to escape the forcing lines that computers have analyzed to the end. For an amateur player who lacks the time to memorize hundreds of moves, that promise sounds valuable.

What stands out is how this product positions itself. It says that in such complex strategic positions, computers often do not know how to handle things. That is a line that makes people nod, because it touches a familiar doubt among chess players: is there still a door for humans against the machine? But that line is out of date.

Twenty years ago, when computers evaluated positions with crude numbers, people had reason to believe that locked, waiting positions were human territory. But modern engines, with neural networks such as Stockfish NNUE or Leela, read these structures reliably. They are no longer baffled by positions with few forcing moves. They can assess the value of every square, every piece, every long-term plan. The argument that computers cannot understand strategic chess, by now, is merely a marketing ploy.

But wait. If we strip away the advertising, the core of the DVD still stands. The move 9...a5 is a sound and coherent idea. It fits the character of the Bayonet Attack: when White chooses a queenside thrust, Black can perfectly well choose a queenside defense. It does not refute the Bayonet, it only slows it down, drawing White into a game in which the advantage of the first move is diluted.

And this is the point where I want to pause. In the world of openings, people often confuse a good idea with a solution. 9...a5 is a good idea. It is not a solution. No move at move nine can neutralize an entire opening system. Anyone who buys the DVD believing they have found an absolute weapon against the Bayonet will be disappointed, because White can always prepare. In the arms race of theory, no defensive line is impregnable.

More tellingly, this product offers not a single number for verification. There is no engine match rate, no average centipawn loss per move, no win-draw-loss statistics from a database. It offers only qualitative judgments: the position is objectively equal, but if Black knows what to do, things may quickly become dangerous for White. That is an honest statement, but an unquantifiable one. Dangerous for White, here, reflects the practical burden over the board, not an objective edge.

One detail troubled me for days. The product's title mentions a figure named ChessMom, with a message of supporting mothers both on and off the board. Yet the entire content is about an opening DVD recommending 9...a5. There is not a single thread linking the title to the content. This is a sign of a data error, perhaps a page-stitching glitch, or a website serving two purposes. For the reader, it is a reminder: before trusting a source, check whether the title really belongs to the content.

I have followed no small number of opening products in more than twenty years in this trade. I have learned one thing: the bigger the promise, the more it needs verification. A DVD can open a new direction for a player, but it cannot replace the player's own work. The board is silent, but every move is an untold story, and that story takes shape only when we walk through it ourselves.

The opening industry is changing. DVDs like this one were once the main tool of amateur players, but today they must compete with online courses, subscription databases, and free analysis tools. The value of a product no longer lies in how many moves it contains, but in how much understanding it gives the player. A good DVD is one that teaches you how to think, not how to remember.

So, if you are the player holding Black against the Bayonet Attack, treat 9...a5 as a skeleton, not a guarantee. Study it, check it with an engine, then test it yourself game by game. And if you are the player holding White, remember that every defensive line has a gap, and your job is to find that gap before your opponent closes it. When the game ends, what remains is not which move was right or wrong, but the question of what we learned from the position.