In the early years of Emperor Huan of the Eastern Han Dynasty, the powerful general Liang Ji dominated the court, acting so arrogantly that he practically ignored the emperor's authority.
Emperor Huan of the Han Dynasty, seeking to break free from the control of the powerful general Liang Ji, conspired with the eunuch Shan Chao and others to kill Liang Ji and reclaim the reins of government.
However, the eunuchs, led by Shan Chao, saw that Emperor Huan of Han was mediocre in ability, so they banded together, planted their cronies throughout the court, seized control of the government, and cruelly persecuted any officials who disagreed with them, creating a situation where the eunuchs held absolute power.
The eunuchs' actions sparked outrage among upright scholars and powerful aristocratic families, who looked upon them with disdain.
During the Han Dynasty, Li Ying, the Colonel of the Metropolitan Police, was a towering figure in intellectual circles. Alongside Guo Chang, the leader of the Imperial Academy students, he openly denounced the eunuch faction, especially Shan Chao, for their corrupt grip on power. In 166 AD, Shan Chao and his allies slandered Li Ying to Emperor Huan, falsely accusing him and Guo Chang of forming a clique to slander the court. Both were arrested, and hundreds were implicated in what became the infamous "Partisan Prohibition" disaster.
Facing the eunuchs' rampant arrogance, all the court officials remained silent as cicadas in cold weather. Only Dou Wu, father of Emperor Huan's empress, stepped forward to speak out for justice. He submitted a memorial to Emperor Huan, vehemently denouncing the eunuchs for ruining the country and harming the people, while pleading for loyal officials like Li Ying. Dou Wu wrote in his memorial:
"If we fail to learn from the past lessons of eunuch usurpation and national ruin, and repeat the same mistakes, then the Han dynasty's empire will be destroyed by eunuchs like Zhao Gao, just as the Second Emperor of Qin was. Moreover, this outcome will occur either by morning or by evening."
After reading the memorial and knowing Dou Wu had always been an upright man, Emperor Huan of Han heeded his advice, pardoned Li Ying and his associates, and gradually distanced himself from the eunuchs Shan Chao and their faction.
Later, the idiom "retracing the overturned cart" came to describe failing to learn from past mistakes and repeating the same errors.
Source: *Book of the Later Han*, Chapter "Biography of Dou Wu"
Meaning of the Idiom: Later, the Chinese idiom "重蹈覆辙" came to describe failing to learn from past mistakes and repeating the same errors.