兵不厌诈

Before the Battle of Chengpu, Duke Wen of Jin asked a practical question: his army was outnumbered by Chu — can virtue win a numbers game? His minister Yong Ji answered with the line that founded the proverb: in matters of ritual, never tire of sincerity; but in the field of battle, never disdain deceit (战阵之间，不厌诈伪).

The duke took the advice. He feigned retreat — pulling back in good order, luring the proud Chu vanguard into a chase that stretched their lines — then turned and broke them at Chengpu. The battle made him hegemon of the states, and made the argument immortal: the battlefield is the one arena where sincerity is a liability.

The Characters

• 兵 (bīng): War, soldiers
• 不 (bù): Not
• 厌 (yàn): To tire of, to disdain
• 诈 (zhà): Deception, feints

Literally: “war does not disdain deceit.” The negation is elegant — it doesn’t endorse trickery; it declines to be scandalized by it. War’s nature includes deception, so deceit in war is not excess. It is the minimum.

The Family It Belongs To

兵不厌诈 is the everyday gate to a whole Chinese tradition of strategic deception:

• 兵者，诡道也 — Sunzi’s doctrine: all warfare is based on deception. The theoretical foundation.
• 三十六计 — the Thirty-Six Stratagems: the tradition’s entire catalog of deceptive moves, from 瞒天过海 to 空城计.
• 知己知彼，百战不殆 — know yourself, know your enemy: which requires denying the enemy the same courtesy. Feints and secrecy are how.

The distinction the tradition maintains: deception aimed at armed opponents in conflict is craft; the same deception aimed at allies, markets, or family is fraud. 兵不厌诈 licenses the first and says nothing about the second.

Usage

• 谈判桌上虚报一个底价?兵不厌诈嘛。 “Quoting a padded bottom line at the negotiation table? All’s fair in war.”
• 商业竞争要有底线,兵不厌诈不适用于合同欺诈。 “Business competition needs a bottom line — ‘all’s fair in war’ does not cover contract fraud.” (The standard caveat, spoken by judges and parents alike.)

Related Chinese Sayings

• 兵者，诡道也 — all warfare is based on deception: Sunzi’s founding doctrine of the tradition.
• 知己知彼，百战不殆 — know both sides, and a hundred battles bring no peril: intelligence is the counter-doctrine.
• 空城计 — the empty city stratagem: deception executed from zero resources.