Stratagem No. 22 第二十二计 Chaos stratagems (混战计)
Shut the door to catch the thief
Literal
Shut the door and catch the thief.
If a small opponent is inside your reach, close the exits and take them. Chase them across open ground and they become dangerous.
Source line
小敌困之。剥，不利有攸往。
Traditional 小敵困之。剝，不利有攸往。
Hem a small enemy in. The hexagram Bo (Splitting Apart): it does not favour having somewhere to go.
Icons working translation — draft, pending review
Bo (Splitting Apart) is the mountain wearing the earth away, and its judgement says it does not favour having somewhere to go. For a small enemy that is the point: take away the road, and do not offer a chase.
三十六计 · Chinese Wikisource edition (public domain)
Meaning
Shut the door to catch the thief means a small opponent is to be enclosed, not hunted across open country. The commentary’s fear is not only that they escape. It is that they escape into someone else’s hands, and that a fugitive with one road left will turn and fight to the death, or will lure the pursuers on. Wu Qi, in the Wuzi, puts a single desperate man in a field and a thousand hunters around him. Every hunter keeps looking over his shoulder. One person with nothing to lose is enough to frighten a crowd.
So the door is a kindness to your own side as well as a trap. Close the exits and a small force can be taken without the desperate last turn. If you cannot close them, the commentary says, let the small enemy go. The classical line limits the trick on purpose. ‘Small enemy’ is doing real work. Corner a large army with no way out and you manufacture the last stand you cannot afford. The hexagram’s warning, that it does not favour having somewhere to go, is aimed at the party inside the ring.
The story
The trap at Ma Yi, 133 BC 马邑之谋
History
In 133 BC, early in Emperor Wu’s wars with the Xiongnu, Wang Hui proposed the door in its pure form. A trader of Ma Yi, in the north of what is now Shanxi, would pretend to betray the town. The chanyu would come inside to take it. A Han army hidden in the valleys would close behind him. The histories give the round ancient figures: some 300,000 Han troops under Han Anguo, with Li Guang, Gongsun He, Wang Hui and Li Xi, and the chanyu Junchen coming with 100,000 cavalry. The design does not depend on the figures. A raider was to be let in, and the way out was to be shut.
The chanyu crossed the border and did not like what he saw. Herds stood in the fields and the people were gone. He seized a local Han officer and got the truth. Then he left, intact, before the door could close. Wang Hui, posted to fall on the Xiongnu baggage, looked at a host that had not been trapped and did not attack. He was later condemned for it. The thief was never in the room. Chasing him was the move this stratagem forbids, and Wang Hui’s refusal is the frightened version of the same rule.
Ma Yi failed because the prey noticed the silence. It is still the textbook of the rule, which is why the stratagem commentary bothers to quote Wu Qi rather than a victory. One desperate man in the open makes a thousand pursuers stare about. Shut his way out and he can be taken. Leave it open and every step of the chase invites a last fight, or an ambush of his own. The Han court learned the price of a door that shows its hinges. The stratagem learned to keep the trick for a small enemy, and to let go when the door will not shut.
The Ma Yi plan, the chanyu’s withdrawal, and Wang Hui’s condemnation are in Sima Qian’s Shiji, the troop figures there are the usual ancient round numbers, and the Wuzi passage is the commentary’s own authority for why a chase fails.
Sources
- Sima Qian, Shiji 史记, ch. 108 and ch. 110
- Wuzi 吴子, chapter Li shi (Encouraging the troops)
Myth check
It is not a general law of no quarter: the line is for a small enemy, and the commentary says that if you cannot shut the door you should let them go. Cornering a large army is how you manufacture a last stand, and the phrase is not in the Art of War.
Modern application
A small leak, a single bad actor inside a building, a short-handed rival team that has overreached into your accounts: close the exits first. Preserve the logs, the doors, the visas, the one bridge they must use, and then talk. A public chase across the market teaches them to run, and a runner with nothing left will burn what they still hold. If you cannot close the door, the old rule is to let the small one go and watch.
The limit matters in competition. Surrounding a much larger opponent so that they have no dignified way out produces the lawsuit, the price war, or the all-night stand you did not budget for. Offer a narrow, real exit when the other side is big. Save the shut door for the case that is actually small, and that is already inside.
Takeaways
- Close the exits before you start the chase.
- Let a small enemy go if you cannot trap them.
- Do not corner a force large enough to stand.
How to counter it
If you are the one inside, look for the silence — empty streets, too-easy bait, a door that was open and is now watched — and leave before the ring closes. If you are outside, do not chase a small party that still has a road; that chase is the trap they want.
Questions
What does shut the door and catch the thief mean?
It means enclosing a small opponent so they cannot run, instead of chasing them in the open. The chase is the danger: a fugitive fights to the death, or leads you on, or falls into someone else’s hands. The hexagram Bo says it does not favour having somewhere to go. If you cannot close the way out, the text says let them go.
Why did the Ma Yi ambush fail?
In 133 BC Han hid a huge army and sent a Ma Yi trader to lure the Xiongnu chanyu in. He noticed empty fields, seized a local officer, learned the plan, and left before the door shut. Wang Hui then refused to chase the baggage and was condemned. The story is the stratagem’s warning: a door that shows itself does not catch the thief.