Cao Fang's Deposition and Plot Against Sima Shi marks the collapse of the young emperor's attempt to recover authority from the Sima brothers. His secret appeal to loyalists is discovered almost immediately, and Sima Shi answers the conspiracy by destroying its participants and replacing Cao Fang with another member of the Cao family.

Court Power and the Plot

After Cao Rui's death, Cao Fang inherited the throne as a child, with Cao Shuang and Sima Yi appointed to share responsibility for him. Cao Shuang gradually took control of the court: he placed his own allies in senior offices, built palaces, took imperial concubines, and removed Sima Yi from military command. Sima Yi withdrew from public life and feigned illness, while his sons likewise kept out of sight. A decade passed before Cao Fang and the few officers still around him tried to reverse the balance of power.

The emperor's remaining allies included Zhang Qi, father of Empress Zhang, Xiahou Xuan, and Li Feng. Together with Cao Fang, they planned to rally loyal men and overthrow Sima Shi and Sima Zhao. The conspiracy invoked an earlier precedent: Cao Fang wrote that Dong Cheng had been killed by his ancestor Cao Cao when a similar plot was uncovered. His companions nevertheless believed Sima Shi less perceptive than Cao Cao and pressed ahead.

Exposure and Punishment

Cao Fang made the appeal tangible by removing his imperial dragon-phoenix shirt and writing the summons in blood after cutting his finger. The garment carried the secret beyond the palace walls. Sima Shi stopped the conspirators by the roadside and asked why they had remained so long with the emperor. They claimed they had been studying the Classics, but he was not persuaded. He found the shirt and recognized the plot.

Sima Shi had Zhang Qi, Xiahou Xuan, Li Feng, and their entire clans executed. He then entered the palace and confronted Cao Fang, who tried to place responsibility on others before admitting his own part in the conspiracy. Sima Shi also held Empress Zhang responsible because she was Zhang Qi's daughter, and ordered her taken away and strangled despite Cao Fang's plea for mercy. The episode thus makes the emperor's family and household part of the punishment, not a refuge from the political reckoning.

Abdication and Significance

Sima Shi called a council of ministers and declared Cao Fang unfit to rule. He persuaded the queen mother to arrange the emperor's abdication and, with her, chose Cao Mao, another member of the Cao family, as successor. Cao Mao did not seek the throne, but had no choice in the matter. The transfer took place in AD 254.

The crisis shows how little authority remained with the emperor: Cao Fang could issue a secret summons, but he could not protect its recipients, his empress, or himself once Sima Shi uncovered it. The change of ruler preserved the appearance of a Cao emperor while leaving the decisive power with Sima Shi. The earlier reference to Dong Cheng's failed conspiracy also gives the episode a pointed historical echo: a plot against a dominant power repeats, but the balance of intelligence and control is now judged in favor of the Sima regime.