The Art of War, Chapter 12: 火攻 (The Attack by Fire)

Chapter 11 dealt with terrain and the pressure of fighting deep in hostile ground. Chapter 12 turns to a single weapon, fire, and then widens into a warning. Fire is powerful and hard to control, so the chapter spends as much time on when not to use force as on how to use it.

Like every chapter in this series, it has three parts: the reading, an analysis of what the chapter argues, and how finance professionals can interpret it in their own work. The original text follows the Chinese Wikisource edition of 《孫子兵法》. The Chinese and English explanations are Claude’s own paraphrase.

Reading the chapter

12.1

原文

孫子曰：凡火攻有五：一曰火人，二曰火積，三曰火輜，四曰火庫，五曰火隊。

中文解說

孫子說：用火進攻有五種對象：第一是燒人員，第二是燒糧草積聚，第三是燒輜重車輛，第四是燒倉庫，第五是燒運輸通道或隊伍。

最後一項「火隊」的解釋不一。有人認為是燒敵軍的行伍，有人認為是燒糧道和運輸線。

English

There are five ways to attack with fire. Burn the troops, burn the stockpiles, burn the baggage trains, burn the storehouses, and burn the 隊.

The fifth term is contested. Some commentators read 隊 as enemy columns or formations. Others read it as supply routes and convoys. Either way, the first four targets are about people and supplies, not ground.

12.2

原文

行火必有因，烟火必素具。發火有時，起火有日。時者，天之燥也。日者，月在箕、壁、翼、軫也。凡此四宿者，風起之日也。

中文解說

放火必須有條件，燃火的器材必須事先準備好。放火要看時機，起火要選日子。所謂時機，是天氣乾燥的時候；所謂日子，是月亮運行到箕、壁、翼、軫這四個星宿的時候。這四個星宿所在之日，正是起風的日子。

English

Fire needs a cause, and the materials must be ready beforehand. There is a right season and a right day. The season is when the weather is dry. The day is when the moon sits in the constellations Winnowing Basket, Wall, Wings or Chariot Platform, which are the days the wind tends to rise.

The astronomy is the traditional way of saying that the wind and weather are predictable enough to plan around. The principle is that conditions must be right and the tools must be ready before the match is struck.

12.3

原文

凡火攻，必因五火之變而應之：火發於內，則早應之於外；火發而其兵靜者，待而勿攻，極其火力，可從而從之，不可從則止；

中文解說

凡是用火進攻，必須根據五種火攻所引起的變化，靈活配合行動：火在敵營內部燒起來，就要及早從外面接應；火已燒起而敵軍仍然安靜不亂，就要等待，不要馬上進攻，讓火勢燒到最大，能乘勢進攻就進攻，不能就停止。

English

Fire attacks must be matched to how the situation changes. If fire breaks out inside the enemy camp, support it from outside early. If fire breaks out and the enemy troops stay calm, wait and do not attack. Let the fire reach its full strength. Follow up if you can, and stop if you cannot.

The important instruction is the last one. The plan includes the permission to stop when the result is not what was expected.

12.4

原文

火可發於外，無待於內，以時發之；火發上風，無攻下風；晝風久，夜風止。凡軍必知有五火之變，以數守之。

中文解說

如果可以從外面放火，就不必等內應，只要看準時機就放火；從上風放火時，不可從下風進攻；白天風刮得久了，夜晚風就會停。凡是軍隊，都必須懂得五種火攻的變化，並用推算天象的方法來等待和把握時機。

English

If fire can be set from outside, do not wait for an insider. Set it at the right time. When the fire starts upwind, do not attack from downwind. A daytime wind that has blown a long time will drop at night. Every army must know the five variations of fire attack and keep watch with calculation.

The upwind and downwind rule is about not standing where the fire can turn on you. The last clause says 以數守之. Commentators differ on whether 數 means calculating the calendar or counting the days and signs. Both readings point to the same habit: watch and compute, do not guess.

12.5

原文

故以火佐攻者明，以水佐攻者強。水可以絕，不可以奪。

中文解說

所以用火輔助進攻，效果明顯；用水輔助進攻，力量強大。不過水可以把敵軍隔斷，卻不能奪取敵人的物資。

English

Using fire to support an attack gives clear results. Using water to support an attack gives strength. But water can cut the enemy off. It cannot seize anything.

Fire destroys, and water divides. Neither of them captures what the enemy holds. This sets up the next passage, which is about what an attack is for.

12.6

原文

夫戰勝攻取，而不修其功者凶，命曰「費留」。故曰：明主慮之，良將修之，非利不動，非得不用，非危不戰。

中文解說

打了勝仗、奪取了土地，卻不能鞏固戰果的，是凶險的，這叫做「費留」，意思是白白耗費、徒然滯留。所以說：英明的君主要深思熟慮，優秀的將領要認真鞏固戰果。沒有利益就不行動，沒有取勝把握就不用兵，沒有危急情況就不開戰。

English

To win battles and take ground but fail to consolidate the gain is dangerous. It is called 費留, wasteful lingering. So the saying goes: an enlightened ruler thinks it through and a good general follows it through. Do not move without a gain, do not use force without a prospect of winning, and do not fight unless the situation is dangerous.

The three negatives in the last sentence are the core rule of the chapter. Winning is not the same as having achieved something. The result has to be secured and has to justify what was spent.

12.7

原文

主不可以怒而興師，將不可以慍而致戰。合於利而動，不合於利而止。怒可以復喜，慍可以復悅，亡國不可以復存，死者不可以復生。故明主慎之，良將警之，此安國全軍之道也。

中文解說

君主不可以因為憤怒而發動戰爭，將領不可以因為惱恨而挑起戰鬥。符合國家利益才行動，不符合利益就停止。憤怒可以重新變為高興，惱恨可以重新變為喜悅，但是滅亡的國家不能再恢復，死去的人不能再復活。所以英明的君主要謹慎，優秀的將領要警惕，這是使國家安定、軍隊保全的道理。

English

A ruler must not raise an army out of anger, and a general must not start a battle out of irritation. Act when it serves the interest, and stop when it does not. Anger can turn back into pleasure and irritation can turn back into contentment. A destroyed state cannot be restored and the dead cannot be brought back to life. So the enlightened ruler is careful and the good general is on guard. This is the way to keep the state secure and the army intact.

The argument rests on an asymmetry. Feelings pass and consequences do not. The passage does not ask for no emotion. It asks that irreversible steps wait until the emotion has passed.

Analysis: what the chapter argues

Fire needs preparation and timing. 12.1 and 12.2 list the targets and then insist on conditions. Fire needs a cause, ready materials, the right season and the right day. Force is not an impulse. It is prepared in advance and used when conditions are right.

The plan responds to what happens. 12.3 sets out how to respond to different outcomes: support the fire from outside, wait if the enemy stays calm, follow up if it works and stop if it does not. The text builds the option to stop into the plan itself.

Do not stand where the fire can turn. 12.4 gives the upwind and downwind rule. The attacker has to keep out of the path of what he starts. The text says that fire needs continuous watching, since the wind changes. This is Claude’s reading of 以數守之, and it is contested. Commentators differ on whether it refers to calendar calculation or to counting signs, but the practical point is the same.

A tool does not decide the aim. 12.5 contrasts fire and water. Both help an attack. Neither takes what the enemy holds. The passage prepares for 12.6, where the question is what the attack achieved.

Winning is not finishing. 12.6 introduces 費留. A win that is not consolidated costs money and time without producing anything lasting. The same passage gives the three conditions for acting: a gain, a prospect of winning and a real danger. Note that the three phrases are rules for when to start. They do not describe how to fight.

Anger is the specific warning. 12.7 says that a ruler or general must not start a war out of anger or irritation. The reason given is plain: moods change, but a lost state and lost lives cannot be recovered. The line 合於利而動，不合於利而止 repeats the rule that action follows interest, not feeling.

Where the reading is contested. The fifth target in 12.1, the meaning of 數 in 12.4, and the astronomy in 12.2 all have more than one reading. The argument above does not depend on any one of these choices.

How finance professionals can read it

This section is Claude’s interpretation. Sun Tzu wrote about armies, and none of the mappings below are his. Fire here is military violence. Claude does not map it to hostile or abusive conduct in business. The parts of the chapter that carry over are restraint, the cost of escalation and irreversible decisions.

Investing

Treat a drastic action as a tool that needs conditions. Fire needs the right season and ready materials (12.2). A large, hard-to-reverse move, such as a concentrated position or a forced sale, calls for a stated reason, prepared funding and a defined trigger, not only a strong view.
Build the stop into the plan. 12.3 says to follow up if you can and stop if you cannot. Write down before entering what result would make you stop, and who decides.
Do not stand downwind of your own position. 12.4 warns against attacking where the fire can turn. An analogy: avoid positions where a reversal would hit your own liquidity, leverage or reputation harder than it hits the market.
Consolidate the gain. 費留 describes a win that is not secured. A profit that is not realised, rebalanced or protected can disappear. A gain on paper has not yet achieved anything.
Apply the three tests before a large move. Is there a gain, is there a realistic prospect of success, and is there a real need? If the answer to the third is no, the move may be optional, and optional moves can wait.

Raising funds

Do not respond to a rejection or a slight with an irreversible step. A founder or treasurer who is angry at an investor, a lender or a term sheet should not walk away from a funding relationship, or accept worse terms just to be done, on the same day. Anger passes. A closed door or a signed term may not reopen.
Escalation has a price. A dispute over terms can be taken further, but a public fight, a threat to withdraw or a short deadline can change how every other investor sees the company. Count that before using it.
Keep an exit from the process. The plan in 12.3 allows for stopping. A raise should have a point at which the team pauses, reconsiders or withdraws, agreed in advance.
Secure what the money is for. 費留 applies to a raise that closes but is not turned into the planned outcome. Funds raised without a plan for use, reporting and follow-through waste the effort of getting them.

M&A

Do not bid out of pique. In a contested process, rivalry, past disputes or wounded pride can push a price above what the analysis supports. 合於利而動，不合於利而止 is the discipline: if the numbers do not support it, stop. Walk-away prices should be set before the auction, not during it.
Be careful with irreversible steps in a heated moment. A signed agreement, a public announcement, a break fee or a termination of talks can be hard to undo. Where the stakes are high, put a pause between the feeling and the signature.
Winning the deal is not the result. 費留 fits an acquisition that closes and is then left unintegrated. The deal creates value only if the post-closing work is done and resourced.
Check the escalation steps. Litigation, hostile positioning or aggressive public statements around a transaction can raise legal, regulatory and reputational issues. Take legal and compliance advice before any such step. Claude is not mapping these to the fire in the text.
Watch for the side that cannot walk away. If a team has spent a long time on a deal, stopping can feel like failure. The chapter treats stopping as part of competence.

Fund management and risk

Separate the decision from the mood after a loss. A drawdown, a failed position or a public criticism creates pressure to do something decisive. Risk policies, position limits and a cooling-off step help ensure that irreversible trades are not made in anger.
Count what cannot be recovered. 12.7 separates feelings, which pass, from outcomes that do not. In risk terms, this is the difference between a drawdown that can be recovered and a loss of capital, a licence or investor trust that cannot.
Make the escalation path explicit. Decide in advance who can authorise a large, hard-to-reverse action and what review it needs.

Across all three

Judgment and temper. The chapter’s strongest line is that anger can pass but a destroyed state and the dead cannot return. The finance version is not about wars. It is that decisions which cannot be undone should not be made in anger or pique. If a decision is irreversible, wait until the feeling has passed and the case still stands on its merits.
Use the three tests. Before escalating, ask whether there is a gain, a realistic prospect of success and a real need. If not, do not move.
Plan the stop. Write down what result would make you pull back, and who has the authority to do it.
Secure the result. Count the work after the win as part of the project.
Keep the limits of these analogies in view. These are readings by analogy. They are not legal, financial or compliance advice, and any step that affects investors, counterparties or regulators should be checked with the relevant professionals.

Questions to carry into the next chapter

Chapter 13 (用間) is the last chapter, and it argues that the cost of a campaign is small next to the cost of not knowing what the other side is doing, so information has to be sought from people.

Which recent decision of yours was driven more by how you felt than by the case, and could it have waited a day?
What result would make you stop your current commitment, and have you written it down?
Where have you won something and not yet consolidated it?