The 9...a5 Move Against the Bayonet: A Clean Solution or Clean Advertising?

In an analysis room at a small chess club on Nguyen Chi Thanh Street in Da Nang, a young player set the board from middlegame back to opening and asked me: if White plays 9.b4, should Black trust the advertising around 9...a5? The question came from an opening product presented as a clear case for Black against the Bayonet Attack in the King’s Indian Defense. The pitch was tidy: 9...a5, few forced lines, play by understanding, no need to memorize. That sounds very appealing to club players. But I have been in this trade long enough to know that when a seller says sound, the buyer must ask: sound compared with what? Based on my experience following games, the best opening recommendations are the ones that know their limits. I thought I had been exiled from the board, but the board took me deeper into myself. The board in this story follows the familiar King’s Indian Defense 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 9.b4. This is the Mar del Plata, Classical system, and 9.b4 is the Bayonet Attack, White’s ambitious queenside push. Black’s main move in this system is 9...Nh5, a choice that leads to more open positions, more forced lines, and a larger role for computers and memory. The product under discussion chooses 9...a5, striking directly at the advanced b4-pawn and seeking queenside counterplay. Technically, 9...a5 is a known secondary line, not a novelty. It does not refute the Bayonet; it opens another strategic road for Black. That point matters because the product’s appeal rests on the phrase few lines, not on a proof that White is lost. I reopened many King’s Indian games to test my feel. 9...a5 creates a position where Black does not have to solve a long forced sequence. Black’s pieces are not fully committed; the queenside can become the main battlefield; White has space but must prove that space is worth something. For a planning player, this is comfortable ground. For a memorizer, it is dangerous ground, because there are no forced sequences to hold on to. In other words, the product sells freedom, but freedom in chess always comes with responsibility. If Black does not understand why to hit b4, when to trade, and when to keep the pawn structure, then few lines becomes few anchors. A good move cannot save a careless advertisement. The most notable point in the source analysis is that every favorable claim comes from the seller. There is no ACPL, no win-draw rate, no engine match rate, and no game sample. The product author says 9...a5 leads to sound positions, objectively equal chances, and danger for White if Black knows what to do. That is the language of a practical equalizing sideline, not a refutation. Readers should translate antidote as a practical, understanding-based equalizer, not as a forced kill. That difference is not small. It decides whether the buyer has the right expectations, and whether the buyer will be disappointed when facing a well-prepared White. One claim should be set aside: the idea that computers do not understand these positions. Modern engines handle King’s Indian Mar del Plata structures well enough that no one should build a whole belief system on that phrase. The author himself concedes that after 9...Nh5, computer analysis becomes important again. That shows engines remain a reliable evaluation tool in this system. The computers do not understand line is a familiar marketing trope in opening products. It is not completely false, because humans still need long-term plans, but it is pushed too far. For an opening product, the promise of beating computers usually means beating the learner’s laziness, not proving that engines are helpless. In market terms, the product targets club-to-master players, roughly 1800 to 2400, who prefer thinking for themselves over memorizing long variations. That is a real segment, but it is smaller than the segment of players who want a main-line system verified by engines. 9...a5 has surprise value because White usually prepares more deeply for 9...Nh5. In open tournaments and club games, that surprise has practical value. But that value is cyclical. When the Bayonet is popular, sidelines such as 9...a5 receive attention. When White finds better ways to handle it, or when engines clarify a small edge, the sideline fades. Buyers should not treat it as a permanent asset; they should treat it as a tool with a shelf life. The interesting part is that the product’s strength is also its weakness. Few forced lines help the player avoid prepared traps, but they also remove clear landmarks. In a non-forcing position, a strategic mistake is not punished immediately by a tactical blow; it appears twenty moves later, when the pawn structure is bad, the queenside is blocked, and Black’s pieces have no counterplay. The learner therefore needs to study plans, not just moves. Why 9...a5? When to trade pawns? When to keep the queenside closed? When to transfer pieces to the center? If a player remembers only move nine and not who owns the next ten moves, that player enters the most dangerous state: holding a correct idea without knowing how to deploy it. Time control deserves a direct word. Slow strategic plans usually suffer in rapid and blitz. In fast games, players need forced moves, sharp blows, and verified escape routes. 9...a5 is not a bad blitz choice, but it is not the optimal weapon for someone who wants to impose tempo through forced lines. If you use 9...a5 in a rapid event, be ready for the opponent to push pawns, open files, trade pieces, and turn the game into a calculation race. At that point, the few lines advantage disappears. This is why I advise young players to keep 9...Nh5 as a backup weapon. A repertoire with one line is easy to read. A repertoire with two lines can breathe. I am not against the product. I am against the way the product is read. A buyer who expects a clean solution to the Bayonet will be disappointed. A buyer who expects a practical, low-theory, strategy-rich alternative will get a useful tool. The difference lies in independent verification. Before adding 9...a5 to a repertoire, open a current database, check a few dozen recent games, verify with an engine, and ask: can White keep a small edge without memorizing? If the answer is yes, 9...a5 is still playable, but the player must know what is being accepted. The board does not lie; the seller is the one who needs checking. For a King’s Indian player, the real value of 9...a5 is the chance to open a game on your own terms. It does not promise a win. It promises a position that Black can play with understanding. In an era when every main line is scanned by engines down to the percentage point, a sideline such as 9...a5 still has a place because it demands different qualities: patience, structural reading, and the courage to accept that not every advantage is measured by one evaluation bar. If you like building plans, 9...a5 is worth trying. If you need an absolute guarantee, go back to 9...Nh5. And if you are the seller, remember: chess players forgive a weak sideline, but they do not forgive advertising that is stronger than the truth of the board.