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 .