Wei Guan Wei Guan ( 220 – 291 ) , Boyu ( 伯玉 ) , formally Duke Cheng of Lanling ( 蘭陵成公 ) , was an official of Cao Wei during the Three Kingdoms period of Chinese history . He served the Jin Dynasty after the end of Cao Wei . Early life and career . Wei Guan was from Hedong Commandery ( present - day Yuncheng , Shanxi ) . His father Wei Ji ( 衛覬 ) was a high - ranking Cao Wei official and a marquess , who died in 229 . Wei Guan inherited his title , and when he grew older became an official . Throughout the years , he became known for his capability and was continuously promoted . After Cao Huan became emperor , he became the justice minister , and was known for his strength in logical thinking . When the Cao Wei regent Sima Zhao commissioned Zhong Hui and Deng Ai to attack Shu Han in 263 , Wei served as Deng ' s deputy . After the fall of Shu Han that year , Zhong planned a rebellion , and the first step of his preparation was to falsely accuse Deng of crimes . Sima Zhao , believing Zhong ' s accusations , ordered Deng arrested , and Zhong in turn ordered Wei to arrest Deng , hoping that Wei would fail and be killed by Deng so that he could further affirm his accusations against Deng . Wei knew this , and surprised Deng in the middle of the night and arrested him successfully . When Zhong later declared his rebellion , Wei pretended to be seriously ill . Zhong therefore did not guard him securely , and later , Wei participated in rousing the troops to kill Zhong and thus end the rebellion . Fearful that Deng would then retaliate him , he had Deng tracked down and killed . When Du Yu publicly denounced Wei , instead of becoming angry and retaliate against Du , Wei visited Du to apologize to him . He also declined a larger fief that Sima Zhao was ready to bestow on him for his accomplishments . Career during the Jin Dynasty . In 265 , Sima Zhao died and was succeeded as regent by his son Sima Yan , who later that year forced Cao Huan to abdicate to him , ending Cao Wei and establishing Jin ( as Emperor Wu ) . Throughout Emperor Wu ' s reign , Wei Guan continued to be an important official and general , serving in a variety of roles capably . As a result , one of his brothers and one of his sons were granted marquess titles . Wei attempted to implement a revised civil service system , where the civil service examiner ( 中正 ) would have less input on grading officials , and actual job performance would become more important , but while Emperor Wu liked Wei ' s suggestions , he did not carry them out . Wei was one of the few officials who dared to openly speak to Emperor Wu about his choice of crown prince , his son Sima Zhong , who was developmentally disabled . On one occasion , Emperor Wu , after Wei hinted that Crown Prince Zhong should not be crown prince , sent a number of inquiries to Crown Prince Zhong to have answered . When the inquiries were appropriately answered ( because Crown Prince Zhong ' s wife Crown Princess Jia Nanfeng had someone else answer the inquiries for Crown Prince Zhong ) , Emperor Wu was happy and publicly showed Wei the answers , embarrassing Wei greatly and making it clear to other officials that Wei had said something . After Emperor Wu ' s death in 290 , Yang Jun , the father of Empress Dowager Yang assumed the regency for Crown Prince Zhong ( who ascended the throne as Emperor Hui ) , but in 291 was overthrown and killed by Empress Jia . Wei was then made regent , along with Emperor Hui ' s granduncle Sima Liang . Wei and Sima Liang tried to get the government on track , but Empress Jia continued to interfere with governmental matters . They also became concerned about the violent temper of Emperor Hui ' s brother Sima Wei the Prince of Chu ( who was heavily involved in the coup against Yang Jun ) and therefore tried to strip him of his military command , but Sima Wei persuaded Empress Jia to let him keep his military command . Sima Wei ' s assistants Qi Sheng ( 岐盛 ) and Gongsun Hong ( 公孫宏 ) thereafter falsely told Empress Jia that Sima Liang and Wei planned to depose the emperor . Empress Jia , who had already resented Wei for having , during Emperor Wu ' s reign , suggested that he change his heir selection , also wanted more direct control over the government , and therefore resolved to undergo a second coup . In summer 291 , Empress Jia had Emperor Hui personally write an edict to Sima Wei , ordering him to have Sima Liang and Wei removed from their offices . His forces thereby surrounded Sima Liang and Wei ' s mansions , and while both men ' s subordinates recommended resistance , each declined and was captured . Against what the edict said , both were killed — Sima Liang with his heir Sima Ju ( 司馬矩 ) and Wei with nine of his sons and grandsons . After Empress Jia , concerned about Sima Wei ' s power , then falsely declared that the edict was forged by Sima Wei and had him executed , Wei was posthumousy honored and created a duke .