“Kill with a borrowed knife” (“Kill with a borrowed sword”, or “Borrow one’s hand to kill”) is a famous Chinese idiom and also the third stratagem of thirty-six. It means to convince others or even your enemies that your enemies are theirs, and make them believe they will be defeated, betrayed or otherwise end up in a very poor position if they do not join the battle.
In the novel, The Romance of the Three Kingdoms, we can find various stories of “killing with a borrowed knife.” For example, Cao Cao used Gongsun Kang’s hands to do the dirty work for him and kill Yuan Shao’s two sons, Yuan Shang and Yuan Xi. Today, let’s discuss another story also involving Cao Cao. However, this story differs totally from others because Cao Cao actually borrowed a sword from his colleague Wang Yun to assassinate their common enemy, Dong Zhuo.
The overlooked detail in a legendary plot
In our previous discussion, we explored the failed assassination attempt by Wu Fu and analyzed why Cao Cao still risked his life to kill Dong Zhuo. However, there is one subtle yet crucial element in this story that often goes unnoticed: why did Cao Cao borrow Wang Yun’s sword instead of using his own?
We know that Wu Fu used his personal dagger in his attempt. But Cao Cao chose to borrow the Seven-Star Precious Sword from Minister Wang Yun. This seemingly minor detail was, in fact, a masterstroke of political strategy.
Strategic Reasons: More than just a weapon
Cao Cao’s decision to use Wang Yun’s sword—rather than any ordinary blade or knife—was not accidental. It was a calculated move rooted in political intelligence and risk management.
Political Binding: Forging an unbreakable alliance
The Seven-Star Sword was a treasured possession of Wang Yun, the minister of the Han court. By borrowing it, Cao Cao effectively bound Wang Yun to the plot. Once the sword was in his possession, Wang Yun could no longer remain neutral. This forced Wang Yun into full complicity, ensuring his continued support.
This act transformed a personal mission into a joint political rebellion.
Identity and Legitimacy: a symbol of authority
Using a sword from a respected minister like Wang Yun gave Cao Cao’s mission official legitimacy. It signaled that this was not a rogue act by a lone officer, but a state-sanctioned effort backed by a key figure in the imperial court.
If the assassination succeeded, Cao Cao would become a savior of the Han dynasty, earning immense political capital and national acclaim.
Personal Calculations: A backup for every outcome
Beyond alliance-building, Cao Cao’s choice revealed his ruthless pragmatism and foresight.
The “Gift” and the escape plan
Cao Cao anticipated possible failure. He knew the assassination might not succeed—so he prepared a plausible cover story.
An ordinary blade could not serve as a believable gift. But the Seven-Star Sword, famed for its craftsmanship and value, was perfect for this ruse. This allowed Cao Cao to transform an assassination attempt into a diplomatic gesture (presenting the sword as a gift) if discovered.
The ultimate betrayal: Shifting blame
Even more chillingly, if all else failed and Cao Cao was captured, he could betray Wang Yun, claiming the minister was the true mastermind who provided the weapon. As the sword’s owner, Wang Yun would bear the primary responsibility, shielding Cao Cao—at least temporarily—from the full wrath of Dong Zhuo.
This reveals the depth of Cao Cao’s self-preservation instinct: every path, even betrayal, was pre-calculated.
Historical Note: Fiction vs. reality
It is important to note that this entire episode is fictional. Historical records such as the Records of the Three Kingdoms make no mention of Cao Cao attempting to assassinate Dong Zhuo or borrowing a sword from Wang Yun. In reality, Cao Cao simply fled the capital after refusing to serve under Dong Zhuo.
The “sword borrowing” and “sword offering” scenes are artistic inventions by Luo Guanzhong in Romance of the Three Kingdoms. Yet, despite their fictional nature, they brilliantly capture the essence of Cao Cao’s character: a man who turns every object, every relationship, and every moment into a tool of political power.
The sword as a symbol
The Seven-Star Sword was never just a weapon. To Cao Cao, it was a political instrument, a symbol of legitimacy, a tool of manipulation, and a lifeboat in failure. By borrowing it, he ensured that whether he succeeded, escaped, or was captured, the narrative would serve his rise.
>> If you are interested, please check how the story develops next.
This is the mark of a true strategist—not just a hero, but a visionary manipulator of fate.
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