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Art of War Chapter 6 Summary: Weak Points and Strong

What Chapter 6 actually argues

The opening verse sets the terms. Whoever is first in the field and awaits the coming of the enemy will be fresh for the fight; whoever is second and has to hasten to battle will arrive exhausted. From this Sun Tzu derives the definition of initiative that runs through the chapter: the clever combatant imposes his will on the enemy and does not allow the enemy's will to be imposed on him. He does it by two levers — holding out advantages so the opponent comes of his own accord, and inflicting damage so he cannot.

The attacking principle follows. Appear at points the enemy must hasten to defend, march swiftly to places where you are not expected, and attack only places that are undefended. Sun Tzu then states the criterion twice from both sides: a general is skilful in attack when his opponent does not know what to defend, and skilful in defence when his opponent does not know what to attack. Both are conditions of the opponent's knowledge, not of your own force.

The middle section is the most rigorous piece of reasoning in the book. If your dispositions are invisible, you can concentrate while the opponent must divide. He must prepare against attack at several points, and so the force he faces you with at any one point is only a fraction of his total. Sun Tzu then runs the consequence through every direction: strengthen the van and you weaken the rear, strengthen the left and you weaken the right, and if you send reinforcements everywhere you will everywhere be weak. Numerical weakness comes from having to prepare against possible attacks; numerical strength comes from compelling your adversary to make those preparations against you.

The chapter closes with the water passage. Do not repeat the tactics that won you one victory; let your methods be regulated by the infinite variety of circumstances. Military tactics are like water, which runs away from high places and hastens downward — so in war, avoid what is strong and strike at what is weak. Water shapes its course according to the ground; the soldier works out his victory in relation to the opponent he is facing. Just as water retains no constant shape, in warfare there are no constant conditions.

Key lines from the Giles translation

These are quoted verbatim from Lionel Giles’ 1910 translation, which is in the public domain:

Whoever is first in the field and awaits the coming of the enemy, will be fresh for the fight; whoever is second in the field and has to hasten to battle, will arrive exhausted.

If he sends reinforcements everywhere, he will everywhere be weak.

So in war, the way is to avoid what is strong and to strike at what is weak.

One modern application: pick the ground nobody is defending

Chapter 6 is the most directly usable chapter for anyone competing against something larger. The instruction is not to be braver or louder on the ground the incumbent has fortified. It is to find the position that is genuinely undefended — the question nobody has answered, the segment nobody is serving, the format nobody is bothering with — and to occupy it before anyone has to hasten anywhere.

The concentration argument gives you the second half, and it cuts both ways. Against a large opponent, their size is also their obligation: they must defend every position they hold, which is why a focused effort can locally outnumber an organisation many times its size. Against yourself, the same logic is a warning. Spreading a small effort across many fronts reproduces the defender's problem voluntarily. If you are reinforcing everywhere, you are weak everywhere, and no one is doing it to you.

The water passage is the caution that stops all of this becoming a formula. The tactic that won last time is now the one your opponent has seen. Sun Tzu explicitly says not to repeat it — the ground has changed shape, and so should the approach.

Where Chapter 6 sits in the 13 chapters

The 13 chapters are a single argument, not thirteen essays: Chapters 1 to 6 establish assessment, cost, the ranking of methods, security, force and concentration; Chapters 7 to 12 apply them to movement, adaptation, observation, ground and restraint; Chapter 13 supplies the information all of it depends on. For the whole arc in one place, read The Art of War explained, or take the printable 13-chapter summary with you. Background on the text, its dating and its translation history is available at Wikipedia.

Read Chapter 6 as a lesson, not a page

LearnTzu turns each of the 13 chapters into short daily lessons with a journal prompt that applies the idea to a decision you are actually facing — which is the difference between having read Sun Tzu and being able to use him.

Frequently asked questions

What is Chapter 6 of The Art of War about?

Chapter 6, Weak Points and Strong, is about initiative and concentration. Sun Tzu argues that arriving first preserves strength, that attacks should land only on undefended positions, and that an opponent forced to prepare against attack everywhere becomes weak everywhere.

What does be like water mean in The Art of War?

It comes from the end of Chapter 6. Water runs away from high ground and hastens downward, so in war you avoid strength and strike weakness. Water also shapes its course to the ground and keeps no constant form, which Sun Tzu uses to argue that there are no constant conditions and no repeatable winning tactic.

Why does Sun Tzu say defending everywhere makes you weak?

Because force is finite. Strengthening the front weakens the rear and strengthening the left weakens the right, so an opponent who must guard several possible points can only meet you with a fraction of his total force at any one of them. Numerical strength comes from compelling those preparations.

How does Chapter 6 define skill in attack and defence?

In terms of the opponent knowledge rather than your own force. A general is skilful in attack when his opponent does not know what to defend, and skilful in defence when his opponent does not know what to attack.