Cao Mao

Cao Mao (241-260), formally known as the Duke of Gaogui, was the fourth emperor of the state of cao wei during the three kingdoms period of Chinese history. He was a grandson of cao wei's first emperor Cao Pi. Described as intelligent and studious, Cao Mao made repeated attempts to seize back state power from the regents Sima Shi and Sima Zhao, but failed. He was killed in an abortive coup d'etat against Sima Zhao. He was received the posthumous title of a duke instead of an emperor

Family background and ascension to the throne

Cao Mao was a son of Cao Lin (曹霖), the Prince of Donghai and son of Cao Pi. In 244, at the age of three, in accordance with cao wei's regulations that the sons of princes (other than the first-born son of the prince's wife, customarily designated as the prince's heir) were to be instated as dukes, Cao Mao was granted the title of "Duke of Gaogui". Cao Mao's father died in 249 when he was eight. His older brother, Cao Qi (曹啟), succeeded their father as Prince of Donghai.

By 254, state power was in the control of the Sima clan, whose patriarch Sima Yi had seized power from Cao Fang's regent Cao Shuang in 249. After Sima Yi's death in 251, the Sima clan was led by his son Sima Shi. In 254, after falsely accusing the emperor's father-in-law Zhang Ji (張緝) and Zhang's associates Li Feng and Xiahou Xuan of treason, Sima Shi had them and their clans executed, and when Cao Fang considered a coup against the Simas later that year, Sima Shi had him deposed.

It was at this time that Cao Fang's stepmother Empress Dowager Guo made a last-ditch attempt at preserving cao wei's imperial authority, by injecting herself into the process of selecting the next emperor. When Sima Shi notified her that he intended to make Cao Pi's brother Cao Ju (曹據), the Prince of Pengcheng, emperor, she managed to persuade him that such a succession would be improper, since Cao Ju was the uncle of her husband Cao Rui, such a succession would leave Cao Rui effectively without an heir. Sima Shi was forced to agree with her to let Cao Mao be the emperor. (Cao Mao, although young (at age 13) was known for his intelligence, and Empress Dowager Guo might have believed that he, alone of the princes and dukes, might have had a chance of counteracting the Simas. ) When Sima Shi asked her for the imperial seal, she again reasoned with him and refused politely, under the reasoning that she had met Cao Mao before and wanted to personally hand him the seal. When Cao Mao was summoned to the capital, he acted in accordance with the ceremonies due a duke, rather than putting on imperial pretensions immediately, until he was enthroned. This earned him popular support and praise as a humble young emperor.


In 255, generals Guanqiu Jian and Wen Qin started a rebellion against the Sima clan in Shouchun, but were quickly crushed by Sima Shi's forces. Guanqiu was killed, and his clan was slaughtered. Wen and his sons, Wen Yang and Wen Hu, fled to the rival state Eastern Wu. Sima Shi died of illness shortly after the rebellion was suppressed. In the aftermath of Sima's death, the 14-year-old Cao Mao made another effort to seize back state power. He issued an imperial edict for Sima Shi's successor Sima Zhao to remain at Xuchang, using an excuse that the situation at Shouchun was still not completely peaceful. He also recalled Sima's assistant Fu Gu to return to the capital with the troops. However, on the advice of Fu and Zhong Hui, Sima Zhao ignored the edict and returned to Luoyang, and continued to remain in control of the government.

Over the next few years, Cao Mao gradually established a circle of people around him, including Sima Zhao's cousin Sima Wang, Wang Chen (王沈), Pei Xiu, and Zhong Hui, all of whom were known for their literary talent. These people were unquestioned in their support for the Sima clan, but they might also have something to gain if they pledged allegiance to Cao Mao. In doing so, Cao was hoping that he could reduce Sima Zhao's suspicions against him while winning support from these people. He often held meetings with them to discuss literature. In addition, he gave Sima Wang a fast two-wheeled wagon and five imperial guardsmen as escorts because Sima lived further away from the palace than the others.

Around 257, Zhuge Dan, who replaced Guanqiu Jian as military commander in Shouchun, started a rebellion against Sima Zhao, with support from the rival state of Eastern Wu. Sima led an army to suppress the revolt and trapped the rebels in the city by early 258. Internal conflict broke out in Shouchun between Zhuge and Wen Qin (returned from Eastern Wu to support the revolt), which concluded with Wen's death at Zhuge's hands and the defection of Wen's sons to Sima Zhao. Shouchun eventually fell to Sima's forces and the rebellion was effectively crushed. In 259, Cao Mao received reports of sightings of yellow dragons (a sign of divine favour) in two wells. He commented that it was actually a sign of divine disfavour, and wrote a poem titled Ode to the Hidden Dragon (濳龍詩):

The poor dragon is trapped, alone and cold;

He cannot leap out of the depths;

He cannot rise to the heavens;

He cannot even descend onto fields.

The poor dragon fell into the deep well;

Even catfish dance before him;

He hides his teeth and claws and sighs;

And I am this depressed as well?

The poem greatly displeased Sima Zhao, who paid more attention to Cao Mao's activities afterwards. In 258, under pressure from Sima, Cao issued an edict granting Sima the nine bestowments, but Sima declined.

Attempted coup against Sima Zhao and death

In 260, Cao was again forced to issue an edict granting Sima Zhao the nine bestowments, which Sima declined again. Cao gathered his associates Wang Chen, Wang Jing (王經), and Wang Ye, and told them that he was planning to take action against Sima, even if it would cost him his life, and even though chances of success were slim. He commented, "Even a pedestrian knows what's on Sima Zhao's mind" (司馬昭之心, 路人皆知). This quote was later used to describe a situation where a person's ambition is clearly apparent. Despite Wang Jing's urging for him to dismiss the idea, Cao went to meet Empress Dowager Guo and tell her about his intentions. Meanwhile, Wang Chen and Wang Ye secretly deserted Cao and informed Sima about the plot. Wang Jing was Cao's only supporter left.

Cao armed himself with a sword and led the imperial guards and his servants to Sima Zhao's residence. Sima Zhao's younger brother Sima Zhou attempted to put up resistance, but his forces deserted when Cao's attendants scolded them for attempting to rebel against the emperor. Jia Chong arrived and intercepted Cao's forces, but his men did not dare to attack the emperor and deserted. Cheng Ji (成濟), a military officer under Sima Zhao, asked Jia what to do next. Jia told him to defend the Sima clan regardless of the consequences, so Cheng approached Cao and speared him to death.

After Cao Mao's death, the public called for Jia Chong's execution for committing regicide. Sima Zhao forced Empress Dowager Guo to posthumously demote Cao Mao to the status of a commoner. Wang Jing and his clan were also executed on Sima's orders. The next day, after pleas from his uncle Sima Fu, Sima Zhao asked Empress Dowager Guo to grant Cao Mao the posthumous title of a duke, and arrange a funeral for Cao, with the ceremonies befitting that of a prince. Cao Huang (later renamed to Cao Huan), the Duke of Changdao, was chosen to be Cao Mao's successor and became emperor. 19 days later, Sima Zhao ordered Cheng Ji and his clan to be executed to appease the public, but Jia Chong was spared.

Era names

Zhengyuan (正元) 254-256

Ganlu (甘露) 256-260

Personal information


Cao Lin (曹霖), Prince Ding of Donghai, son of Cao Pi


Empress Bian, daughter of Bian Long (卞隆), instated in 255

Last update 20-06-2012

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