During the late Eastern Han Dynasty, Yuan Shao's two sons, Yuan Tan and Yuan Shang, turned against each other in a bitter power struggle, and after a decisive defeat, Yuan Tan was forced to flee for his life.
Yuan Tan's advisor Guo Tu said to Yuan Tan, "Your army is small and your provisions are scarce, so you cannot defeat Yuan Shang. It would be better to request Cao Cao's help. If Cao Cao agrees, he will send troops to attack Ye first. If Yuan Shang is defeated, you can absorb his forces and seize his territory. Then you can contend with Cao Cao."
Yuan Tan said, "My father lost to Cao Cao at Guandu. I will never coexist with Cao Cao. If I go to beg him now, he won't agree." Guo Tu said, "We can first negotiate peace with him, then ask for his help." Yuan Tan pondered for a long time and said, "Who should I send to speak with Cao Cao?" "Xin Pi."
Xin Pi was sent to meet Cao Cao. Cao Cao was planning to attack Liu Biao in Jingzhou, but upon hearing that Yuan Tan was willing to make peace, he was delighted and agreed to first attack Ye.
A few days later, Cao Cao hosted a banquet for Xin Pi, but throughout the meal, he never once mentioned attacking Ye—it turned out Cao Cao still intended to march on Jingzhou instead.
Xin Pi then raised the matter of negotiating peace and urged Cao Cao to send troops to attack Ye.
Cao Cao thought for a moment and said, "Is Yuan Tan truly seeking peace with me?" "Truly," Xin Pi replied. "Yuan Shang has strong troops and sturdy horses—can I defeat him?"
“Definitely,” Xin Pi said. “Yuan Shang’s army is a desperate and exhausted force, while your reputation is known throughout the world, and your troops are invincible in battle. Defeating Yuan Shang will be like a swift wind shaking autumn leaves—you will surely achieve immediate victory!”
Cao Cao burst into hearty laughter and agreed to make peace with Yuan Tan, promising to send troops to attack Ye.
Later, "Swift Wind Shakes Autumn Leaves" evolved into the idiom "Autumn Wind Sweeps Leaves," used to describe a clean sweep, leaving nothing behind.
Source: *Records of the Three Kingdoms*, "Book of Wei, Biography of Xin Pi"
Meaning of the Idiom: Later, the Chinese idiom "秋风落叶" came to describe a clean sweep, leaving nothing behind.