Brief: This article recounts the diplomatic masterpiece of Zhu Zhiwu in 630 BCE, who single-handedly saved the State of Zheng from a joint siege by Qin and Jin. Facing the Qin army, the elderly minister was lowered by rope over the city walls to meet Duke Mu of Qin. Through masterful rhetoric, he argued that destroying Zheng would only strengthen the rival Jin state, while sparing it would benefit Qin as a “host” for travelers. His logic – famously stating that “your neighbor’s strength is your weakness” – convinced the Duke to withdraw and form an alliance, forcing Jin to retreat.
During the exile of Chong’er, when he passed through the State of Zheng, Duke Wen of Zheng failed to receive him with due courtesy, thus sowing the seeds of personal resentment.
In the Battle of Chengpu in 632 BCE, Duke Wen of Jin (Chong’er) defeated the State of Chu, establishing his position as hegemon over the central states. In this conflict, Zheng had contributed troops to support Chu against the Jin-led coalition, further intensifying Duke Wen of Jin’s dissatisfaction with Zheng.
Duke Wen of Jin was angered by Zheng’s “fence-sitting” diplomatic tendencies during the power struggle between Jin and Chu. Zheng had ostensibly submitted to Jin while secretly maintaining ties with Chu, a stance that deeply frustrated the Jin ruler.
In 630 BCE, the Qin and Jin states besieged Zheng, for Zheng had shown disloyalty to Jin and relied on its proximity to Chu.
Jin’s army was stationed at Hanling, Qin’s at the south bank of the Si River.
Yi Zhihu, a senior official of Zheng, said to the Duke of Zheng:
“The state is in peril! If you can send Zhu Zhiwu to persuade the ruler of Qin, their army will surely withdraw.”
The Duke agreed. But Zhu Zhiwu declined, saying:
“In my prime, I was not as capable as others; now that I am old, I can do even less.”
The Duke said:
“I failed to employ you earlier, and now in our urgency I come to you – this is my fault. Yet if Zheng falls, it will bring you harm as well!”
Zhu Zhiwu then consented.
At night, Zhu Zhiwu was lowered from the city wall by rope. He went to see the Duke of Qin and said:
“Qin and Jin have besieged Zheng. Zheng knows it will perish. But if the fall of Zheng benefits you, sire, I dare trouble your men. Yet crossing a neighboring state to rule distant land – you know how difficult that is. How can you use Zheng’s demise to strengthen your neighbor? Your neighbor’s strength is your weakness. If you spare Zheng and treat it as your host for travels east, your envoys will have provisions, and no harm is done to you.”
Zhu Zhiwu continued:
“Moreover, you once granted favors to the Duke of Jin (Duke Hui), who promised you the cities of Jiao and Xia. Yet he entered Jin in the morning and fortified his borders by evening against you – as you well know. What satisfaction does Jin have? Once it conquers Zheng to its east, it will surely expand westwards. If it does not weaken Qin, where will it gain territory? Weakening Qin to benefit Jin – I leave this for your consideration.”
The Duke of Qin (Duke Mu of Qin) was pleased and made a pact with Zheng. He appointed generals including Qi Zishu, Feng Sun, and Yang Sun to guard Zheng, then withdrew his army.
Zi Fan, (Hu Yan, a Jin commander), requested an attack on Qin’s forces. Duke Wen of Jin said:
“Without the strength of that man (the Duke of Qin), I would not be where I am today. To harm someone after benefiting from their strength is unrighteous; to lose an ally is unwise; and to replace unity with chaos goes against martial honor. Let us also withdraw.”
So the Jin army, too, departed.
Note
Zhu Zhiwu
An elderly, wise diplomat of the Zheng state. He saved his country by bravely going out alone to persuade the enemy commander to withdraw.
Duke Mu of Qin
Ruler of the Qin state. He was rational and self-interested, and he accepted Zhu Zhiwu’s logical argument to pull back his army.
Duke Wen of Jin (Chong’er)
The powerful hegemon of Jin. He held a grudge against Zheng and allied with Qin to besiege it, but later retreated to honor his past gratitude to Qin.
Duke of Zheng
Ruler of the weak Zheng state, who begged Zhu Zhiwu to save the nation in crisis.
Hu Yan (Zi Fan)
Loyal advisor to Duke Wen of Jin, who wanted to attack Qin after Qin switched sides.
Spring and Autumn Period (770–476 BCE)
An era of shifting alliances and power politics, where small states survived by wise diplomacy.
Siege Warfare
A military tactic where two powerful states (Qin and Jin) surrounded and threatened a small state (Zheng).
Diplomatic Realism
Making decisions based purely on national interest, not loyalty or emotion.
Fence‑sitting diplomacy
A small state’s tactic of secretly leaning toward two rival powers to survive.
Lowered from the wall by rope
Zhu Zhiwu snuck out of the besieged city at night because the gates were blocked.
Your neighbor’s strength is your weakness
Zhu Zhiwu’s core logic: if Qin helps Jin destroy Zheng, Jin will grow stronger and threaten Qin.
Sparing Zheng as a host for travelers
Zhu Zhiwu promised Zheng would supply Qin’s envoys in the future, like a roadside hotel.
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