9...a5 and 'a night unlike any other': rereading an opening promise

Three in the morning in Binh Duong. The screen is still lit, the coffee long cold, and on the board sits the position after White's ninth move: 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. I have sat with this position across many nights, but this week has a concrete reason: an opening DVD has just been released, titled like a chapter of a novel — A night unlike any other.

What does the product promise? It asks the player handling Black, after White chooses the Bayonet Attack 9.b4 in the King's Indian Defence, to answer with 9...a5. Not with 9...Nh5, the main line every book, every database and every coach names first. Rather with a quiet flank pawn move, sounding like a long exhale, an act of patience.

What made me stop was not the move itself. It was how the move is sold, and how people talk about it.

The King's Indian is the most philosophical defensive system in modern chess. Black hands White the centre, folds behind the d6–e5 pawn chain, then counterattacks with a kingside storm. One side builds a house, the other burns one. White advances on the queenside, Black on the kingside, and whoever arrives first survives. Garry Kasparov made it a principal weapon throughout his career, after Bobby Fischer and Mikhail Tal had opened the road in earlier decades.

The Mar del Plata variation takes its name from the tournament in that Argentine coastal city in 2026, where the system 7...Nc6 8.d5 Ne7 first took shape as an independent theoretical block. It was also the era in which world chess memory bound itself to one specific structure: White pushes d5, Black reroutes the knight from c6 to e7, and both sides sign an unspoken contract never to retreat.

The Bayonet Attack 9.b4 came later, gaining popularity from the late 1980s and exploding in the 1990s, when Judit Polgar and a generation of attacking players turned it into an instrument of torture. The idea is blunt: White grabs queenside space, prepares Ba3, pushes b5 when convenient, and turns the queenside threat into a rhythm faster than the storm on the other side of the board.

Before 9.b4, Black's main answer is 9...Nh5. The knight leaps to the rim, preparing ...f5, accepting that the kingside will decide everything. It is a highly forcing move, mined down to its final layers of theory. Precisely for that reason, a section of Black players is always hunting for another exit.

That is the context for 9...a5.

One thing must be said at once about my material. Everything I could access is promotional copy, with no reference games, no database frequency statistics, no engine evaluations, no average centipawn loss for the move, and no clear identification or track record for the author. For an opening DVD sold to serious players, that is a large gap. Every technical claim drawn from it, including in this article, should be read as pending verification.

So what does 9...a5 actually do? The flank pawn immediately questions the b4 pawn that has just advanced. White is forced to declare intent on the queenside before Black commits to anything on the kingside. If White keeps the tension with Ba3, Black gains time to finish development and choose between ...Nh5, ...Nc8 or ...Nd7 depending on the shape. If White trades, the queenside structure opens in a direction unfavourable to the attacker, and Black acquires the a-file and invasion squares.

In other words, Black is not trying to refute the Bayonet. Black is trying to drag it into a different war, one where speed is no longer the decisive weapon.

The product's own author concedes in the introduction that objectively the chances are equal. That is the most important detail in the entire document, and it accidentally confesses what every opening product tries to hide: the real value of 9...a5 lies in preparation asymmetry, not in objective superiority.

The buyer is not paying for a stronger move. The buyer is paying for the ability to enter a game the opponent understands less well.

This is the point I find most worth discussing, and the one the Vietnamese chess community rarely states outright. In tournament halls, preparation advantage is a form of purchasable capital. It breaks no rule, harms no one, and works with cruel efficiency. A move that is theoretically weaker but forces the opponent to spend clock time at move fifteen can still win the game.

The problem lies elsewhere: the product's central sales argument. The material asserts that computers often do not know how to handle the complex strategic positions arising after 9...a5.

That argument is dated. Since 2026, when deep-learning engines such as AlphaZero and Leela reset the standards for evaluating closed positions, and then in 2026 when NNUE technology brought neural networks into conventional engines, the gap between machine and human in centre-conceding structures has narrowed substantially. Today's engines are no longer confused by positions with few forcing moves. They evaluate them through indices the human eye does not read out, and they do so fairly consistently.

Based on my experience following and commentating games across many seasons, the belief that 'the machine does not understand closed positions' is still passed around like a comforting mantra. It comforts those who do not want to memorise, rather than reflecting the machine's actual capacity.

The remaining claim, and the most valuable one, is that 'very few concrete lines need to be remembered' — meaning the Black player only needs the plan rather than a string of moves.

This is the most attractive and least verifiable promise. A repertoire built on 9...a5 still needs at least two other things. First, fallbacks for every White branch that avoids 9.b4: 9.Ne1, 9.Nd2, 9.Bg5 and other slow but toxic choices. Second, knowledge of 9...Nh5 itself, because White can steer back into familiar structures after Black has played 9...a5.

Put differently, 9...a5 saves the Black player part of the memory load, but it is not free. It swaps one debt for another.

There is one more question the material never answers: product scope. Does the DVD cover only the 9.b4 branch, or the entire King's Indian complex after 7...Nc6? For the buyer, that is the difference between a chapter and a book. Left unstated, the only way to find out is to buy and check.

And here I want to linger a little longer, because it concerns a habit of an entire generation of players.

In the collective memory of the chess world, 'playing by plan' always ranks above 'playing by lines'. The one who memorises is a tradesman; the one who understands the position is an artist. The title A night unlike any other strikes exactly that longing: a bayonet night, a night raid, an act of defiance. It sells the player the feeling of doing something bold, while in fact they are buying a rearrangement of knowledge that has existed for a long time.

Our greatest blind spot is not failing to know 9...a5, but equating the feeling of understanding with actual advantage.

I once sat in the stands of a domestic tournament, watching a young player spend twenty minutes on move eleven, entirely calm, entirely confident, then lose in forty moves. He understood the plan. He did not understand his position.

There is something worth remembering about how theory moves. Most of what is called a 'new discovery' in opening products is really the repositioning of an old sideline at a new moment in theory. 9...a5 is not a discovery. It is a legitimate but minority line, repositioned. The difference between those two things is the difference between history and marketing.

For club players and improvers — the audience the material itself targets — this is entirely fine. No one should be ashamed of buying a plan instead of a miracle. But for elite players, who cannot abandon forcing lines merely because they are hard to remember, 9...a5 has value only as a reserve branch, a spare drill in the toolkit.

The board keeps the calluses of a human life, not only the pieces.

When an opening product is packaged as a special night, it is easy to forget that behind it lie thousands of hours of rewinding old games. Sixty days of listening to recordings, I imagined the roar of empty seats — and in this case, that roar is the click of a mouse.

So what should a buyer do?

First, demand evidence. An opening product worthy of your money should publish reference games, database figures, and at least one quantitative comparison with 9...Nh5. Silence on those numbers is itself information.

Second, remember that preparation advantage has a short shelf life. A minority line, once put into a book, is quickly analysed and neutralised by the strongest opponents. The only thing that lasts longer is your own capacity to understand positions.

Third, choose according to how you actually play. If you like to sit still, calculate, endure and wait for the opponent to err, 9...a5 is a choice worth studying. If you need the certainty of forcing play to feel secure, 9...Nh5 is still there, still patient, still holding its value.

Age does not extinguish love for the board, it only changes its colour. And chess remains what it has always been: it does not reward those who believe, it rewards those who verify.

With no spectators, chess returns to the sound of its own breathing. Opening DVDs, promises, bayonet nights — all of it is applause that rings out before the game begins.

Applause rang out amid defeat, and I understood that chess promises no victory. It promises only that, on move eleven, you will have to decide who you are.

The game ends, but the applause still echoes in my memory.