Brief: This article recounts the ingenious stratagem of Ru Er, a scholar of the Warring States period, who single-handedly saved the small kingdom of Wey from annihilation by Wei in 311 BCE. Facing a superior army, Ru Er employed a masterful three-stage psychological operation. He first convinced the warmongering minister, Chengling Jun, that mercy was in Wei’s best interest. He then planted a seed of suspicion in King Ai of Wei, suggesting the minister had been bribed. When the minister followed the script and advocated withdrawal, the King’s jealousy ignited, leading him to recall the army and exile his own minister to punish the perceived betrayal.
In 311 BCE, during the eighth year of King Xiang of Wei’s reign, also known as King Ai of Wei, the state of Wei launched a full-scale invasion of the small kingdom of Wey. Wei’s forces swiftly captured two cities, and the Wey capital of Zhaoge trembled on the brink of collapse. King Si of Wey, desperate and helpless, saw no way to save his realm – Wey had neither armies nor allies.
Then came Ru Er, a scholar from Wei himself, who boldly requested an audience. He declared,
“I can make the Wei army withdraw, and have Chengling Jun – the mastermind behind this war – removed from power.”
Overjoyed, King Si vowed:
“If you succeed, Wey will honor you and your descendants forever!”
Ru Er knew brute force was useless. His plan required precision, timing, and deep insight into human weakness. He aimed not just to halt the invasion, but to destroy its architect: Chengling Jun (Lord Chengling), a powerful minister whose influence drove Wei’s aggression.
His strategy unfolded in three masterful stages.
Stage One: Persuade Chengling Jun
Ru Er first met Chengling Jun (Lord Chengling) in secret. “If Wei destroys Wey,” he argued, “Wey will flee westward and seek aid from Qin. Qin has long coveted the east – if it intervenes, Wei gains nothing but earns a powerful enemy. But if Wei shows mercy, Wey will become a loyal vassal, shielding Wei from Qi and Zhao. Which is truly wiser?”
Convinced, Chengling Jun agreed to advise the king to withdraw.
Stage Two: Plant suspicion in the King’s mind
Ru Er then went alone to King Ai of Wei (King Xiang of Wei). He said,
“Wey is of the Ji clan – the royal Zhou lineage – and holds great treasures. Yet in its hour of need, it offers none to you. Why? Because it believes this war is Chengling Jun’s personal scheme. Even if Wey sent gifts, they’d never reach Your Majesty.”
He added ominously:
“Whoever first urges leniency toward Wey is surely being bribed by them.”
Stage Three: Let the trap snap shut
Days later, Chengling Jun entered the palace to recommend withdrawal – just as Ru Er predicted. The moment the words left his lips, King Xiang recalled Ru Er’s warning. Convinced his minister was colluding with Wey for personal gain, the king erupted in fury. He immediately:
- Ordered the Wei army to retreat;
- Stripped Chengling Jun of all titles, banishing him from court forever.
Wey was saved without firing a single arrow. Ru Er became its savior. And Chengling Jun, unaware he’d been played, vanished into obscurity.
Recorded in both the Records of the Grand Historian and the Strategies of the Warring States, this episode reveals the brutal calculus of the era: small states survived not through strength, but through cunning. Trust between ruler and minister was fragile – one whisper of “secret dealings with foreigners” could topple even the most powerful official.
Ru Er’s genius lay in speaking different truths to different ears: to Chengling Jun, he offered logic and long-term interest; to the king, he fed paranoia and jealousy. With no weapons, only words, he halted an army and reshaped a court. In the age of the Warring States, such a man was worth more than ten thousand soldiers.
Note
Ru Er
A brilliant Warring States strategist who used psychological deception to save the tiny state of Wey from being destroyed by Wei. He turned a minister and a king against each other without fighting.
Chengling Jun (Lord Chengling)
The powerful war‑favoring minister of Wei who planned the invasion of Wey. He was manipulated and disgraced by Ru Er.
King Ai / King Xiang of Wei
Ruler of Wei who was easily suspicious. He believed his minister was bribed and recalled his army.
King Si of Wey
The desperate ruler of the small state Wey, who had no army to defend himself.
Psychological Warfare (Deception Stratagem)
Winning a conflict using words, suspicion, and human weakness instead of soldiers.
Divide and Rule
Ru Er’s core tactic: split the trust between a ruler and his top minister to make the enemy destroy themselves.
Small State Survival
In the Warring States era, weak countries survived by wisdom and diplomacy, not military power.
Wey
A tiny, weak state surrounded by powerful neighbors; it could only be saved by trickery.
A web of deception
Ru Er’s three‑step plan that trapped both the minister and the king.
Defeat an army without a fight
The highest form of strategy: making the enemy retreat on their own.
Suspicion destroys power
A ruler’s distrust can ruin even his most important officials.
One strategist = ten thousand soldiers
The value of clever politics over brute force.
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