In 68 BCE, Emperor Xuan of Han dispatched the imperial attendant Zheng Ji and commandant Sima Xi to lead a group of pardoned criminals to the Quli region on the northwestern frontier, where they were to establish military colonies and stockpile grain locally, preparing to attack the state of Jushi, located over a thousand li from Quli.
After the autumn harvest, Zheng Ji and Sima Xi led a large army to attack the Kingdom of Cheshi. The king of Cheshi, knowing he could not defeat the Han forces, sought help from the Xiongnu. But the Xiongnu did not send troops in time, so the Cheshi king had no choice but to surrender to the Han dynasty. Zheng Ji stationed 300 soldiers in Cheshi to farm the land, while he led the rest of his troops back to Quli.
When the Kingdom of Jushi surrendered to the Han Dynasty, the Xiongnu quickly realized that Jushi's fertile lands and proximity posed a threat, so they sent cavalry to attack.
When the kingdom of Jushi sent envoys begging for aid, Zheng Ji mustered over a thousand soldiers from the Quli garrison and marched to their rescue.
However, the Xiongnu forces were overwhelming, vastly outnumbering the Han troops, and Zheng Ji found himself besieged. He sent a messenger to break through the encirclement and request reinforcements from Emperor Xuan of Han. Upon receiving the frontier report, the emperor summoned his ministers for discussion. General Zhao Chongguo advised, "The Xiongnu are currently in a weak position. If we attack their right flank, they will be forced to withdraw their troops to defend themselves, thereby lifting the siege on Cheshi."
Prime Minister Wei Xiang opposed sending troops to attack the Xiongnu, arguing, "In recent years, the Xiongnu have not invaded our borders, so attacking them over the Cheshi kingdom would be unjust. Our border people are struggling to survive, and we cannot afford war lightly. Domestically, many officials are incompetent, so we must first focus on governance and reform court affairs. Even if we defeated the Xiongnu, victory would bring future troubles. Relying on our nation's size and population to flaunt military might is arrogance, and an arrogant army is doomed to fail!"
Emperor Xuan of Han, after hearing Wei Xiang's counsel, adopted his advice and abandoned plans to reinforce the Cheshi garrison. Instead, he dispatched the Marquis of Changluo, Chang Hui, to mobilize troops from Zhangye and Jiuquan, positioning them near Cheshi as a show of support.
When the Xiongnu scouts learned of this, they withdrew their forces, and Zheng Ji led his troops back to Quli.
Later, the idiom "An Arrogant Army Is Doomed to Defeat" came to describe that a prideful military is certain to lose.
Source: *Book of Han*, Chapter "Biography of Wei Xiang"
Meaning of the Idiom: Later, the Chinese idiom "骄兵必败" came to describe a prideful military is certain to lose.