Coup of Cao Mao

The coup of Cao Mao was a coup d'etat that occurred in 260 in Luoyang, the capital of the state of Cao Wei, during the Three Kingdoms period. Cao Mao, the nominal emperor of Wei, attempted to launch a coup to oust the regent Sima Zhao, who effectively controlled the Wei government. However, the coup concluded with Cao Mao's death and Sima Zhao retaining his status. Contrary to its intention, the coup actually increased the Sima clan's power and influence in Wei, thus providing a foundation for the eventual usurpation of the Wei throne in 265 by Sima Zhao's son Sima Yan, who founded the Western Jin Dynasty.

The coup is also mentioned in the historical novel Romance of the Three Kingdoms by Luo Guanzhong, which dramatises the history of the late Eastern Han Dynasty and the Three Kingdoms period. The events of the coup described in the novel are largely similar to that described in historical sources.

Background
The state of Cao Wei was established in 220 by Cao Pi, which marked the start of the Three Kingdoms period in China. The authority of the Wei imperial family had been weakening since the death of the second Wei emperor, Cao Rui, and reached a nadir after the Incident at Gaoping Tombs in 249, when the Wei general Sima Yi seized power from the regent Cao Shuang. Sima Yi died in 251 and was succeeded by his sons Sima Shi and Sima Zhao, who effectively controlled the Wei government.

In 254, Sima Shi deposed the third Wei ruler Cao Fang and installed a 13-year-old Cao Mao on the throne. From the start of his reign, Cao Mao acted in defiance of the Simas, refusing to accept the imperial seal directly from Sima Shi, and, after Sima Shi's death in 255, he attempted to order Sima Zhao to remain in Xuchang to keep watch over Shouchun (present-day Shou County, Anhui), where a rebellion led by Guanqiu Jian and Wen Qin had just been suppressed. However, Sima Zhao ignored Cao Mao's edict and returned to the capital Luoyang. While Sima Zhao administered state affairs, Cao Mao attempted to gain the favour of the literati in the court through unremarkable meetings to discuss literature with some officials - Sima Zhao's cousin Sima Wang, Wang Shen (王沈), Pei Xiu, and Zhong Hui. Cao Mao also provided Sima Wang with a chariot and five imperial guardsmen as escorts because the latter lived further away from the palace than the others.

In 258, Sima Zhao incited his supporters to force Cao Mao to publicly offer him the nine bestowments, which he ostensibly refused as a showcase of his "humility". A year later, Cao Mao received sightings of yellow dragons in two wells, and he wrote a poem identifying the dragons as being trapped inside wells and likened himself to the dragons. With his suspicions aroused, Sima Zhao forced Cao Mao to offer him the nine bestowments but he declined again. Cao Mao perceived this as a sign to act immediately for his clan to regain control of the Wei government.

The coup
In 260, when he was 19, Cao Mao gathered his associates Wang Shen, Wang Jing and Wang Ye, as well as 300 soldiers, declaring his intention to make a last-ditch attempt to overthrow Sima Zhao, even at the cost of his life. He remarked, "Every person on the street knows what is in Sima Zhao's mind" (司馬昭之心，路人皆知), and this quote later became a famous saying used to describe a situation where a person's intention or ambition is rather obvious.

Wang Jing advised the emperor against such action, but Cao Mao ignored Wang's advice and informed Empress Dowager Guo of his plan. In his absence, Wang Shen and Wang Ye secretly deserted Cao Mao and notified Sima Zhao about the plot, leaving only Wang Jing to support the young emperor.

Cao Mao then led his forces to Sima Zhao's residence, where Sima Zhao's younger brother Sima Zhou attempted to put up resistance, but gave up when the Cao Mao's attendants scolded them for defying the emperor. Sima Zhao's aide Jia Chong showed up and intercepted Cao Mao's forces but his men did not dare to attack the emperor. When Cheng Ji (成濟), a military officer under Jia Chong, asked Jia what to do, Jia told him to defend the Sima clan regardless of the consequences. Cheng Ji then approached Cao Mao and killed the emperor with his spear.

Aftermath
After Cao Mao's death, the public called for Jia Chong's execution on the grounds that he had committed regicide. Sima Zhao forced Empress Dowager Guo to posthumously demote Cao Mao to the status of a commoner, and then ordered Wang Jing and his clan to be executed. The following day, after pleas from his uncle Sima Fu, Sima Zhao asked Empress Dowager Guo to posthumously instate Cao Mao as the "Duke of Gaogui" (高貴鄉公) and he arranged a funeral for Cao Mao, with the ceremonies befitting that of a prince. Cao Huang (later renamed to Cao Huan), the Duke of Changdao (常道鄉公), was chosen to succeed Cao Mao and was installed on the throne. 19 days later, Sima Zhao had Cheng Ji and his family executed to appease public anger but Jia Chong was spared.

Sima Zhao successfully retained his power during the coup and eliminated his opponents in the Wei court, leaving only the young Cao Huan as a puppet emperor under his control. He did not take the Wei throne, even until his death, but was granted the title of a vassal king - "King of Jin" (晉王) - and the nine bestowments by Cao Huan in 264. Sima Zhao died in 265 and was succeeded by his son Sima Yan, who forced Cao Huan to abdicate in his favour and established the Western Jin Dynasty.

Modern references
In the seventh instalment of Koei's Dynasty Warriors video game series, a stage is dedicated to the initial coup d'etat against Sima Zhao, where it is called "Wei's Emperor's Last Stand"; the other two are mentioned in the narration.