Sima You (Chinese: 司馬攸; pinyin: Sīmǎ Yōu; 246[2] – 27 April 283[3]), courtesy nameDayou (大猷), posthumously known as Prince Xian of Qi (齐献王), was an imperial prince of the Western Jin dynasty of China. He was the second son of Sima Zhao, a regent of the Cao Wei state during the Three Kingdoms period, and Zhao's wife Wang Yuanji. His wife was a daughter of Jia Chong and Jia's first wife Li Wan; Li Wan herself was a daughter of Li Feng.
Sima You became the heir to his uncle, Sima Shi, who eventually died without any sons. It is known that Sima You was a person of mild-mannered character, who was expected to become King of Jin, but ended up being passed over due to his young age. The heir that was eventually chosen was Sima Zhao's first son, Sima Yan (Emperor Wu), who usurped the Cao Wei throne and established the Jin dynasty with himself as the new emperor in February 266. Sima You was made Prince of Qi on 9 February 266.[4]
When Emperor Wu appointed his developmentally disabled son heir apparent, he was concerned that his subjects viewed Sima You too favourably. One such incident occurred between August 272 and 274,[5] while Xiahou He was still Intendant of Henan. Emperor Wu had become gravely ill, and the Jin court considered making Sima You the next emperor, rather than Emperor Wu's son and crown prince Sima Zhong. Xiahou told Jia Chong, "Your relations with both sons-in-law are equal. A heir should be chosen based on his virtues." Jia did not comment on the statement; after Emperor Wu heard about the incident, he moved Xiahou to the post of Minister of the Household, and deprived Jia of his military command, while allowing Jia to retain his titles and treatment in court.[6] Despite this, Emperor Wu continued to bestow titles upon Sima You, including the post of sikong on 16 September 276, replacing Jia Chong (who was made Grand Commandant).[7]
In order to strengthen his son's position, he ordered Sima You away from Luoyang in January 283[8] to his fiefdom of Qi, despite protestations from their sisters, Princess Jingzhao and Princess Changshan.[9] With his father-in-law Jia Chong having died a few months earlier in May 282, Sima You had one fewer powerful voice to intercede on his behalf. Sima You fell ill from the stress and died soon after in April 283 at the age of 38 (by East Asian age reckoning).[10]
^Jia Chong's biography in Book of Jin recorded that Sima You and Jia Bao were wedded before Jia Chong was supposed to lead an army to guard the Guanzhong region and fend off attacks from Di and Qiang (氐羌) rebels in Sep 271.
^Although Sima You's biography in Book of Jin indicated that he was 36 (by East Asian reckoning) when he died, his biography also indicated that he was 10 (by East Asian reckoning) when Sima Shi died (in March 255). In addition, his biography also indicated that he was older than 18 (by East Asian reckoning) when the "five-rank peerage" system was reinstated (in 264), which would not be the case if his birth year is 248. Thus, his age at death should be greater than 36 (by East Asian reckoning).
^According to Sima Yan's biography in Book of Jin, Sima You died on the guichou day of the 3rd month of the 4th year of the Taikang era of his reign. This corresponds to 27 Apr 283 on the Julian calendar. [(太康四年三月)癸丑，大司马齐王攸薨。] Jin Shu, vol.03
^dingmao day of the 12th month of the 1st year of the Tai'shi era, per Sima Yan's biography in Book of Jin.
^According to the chronology of Jia Chong's biography in Book of Jin, the incident between him and Xiahou He took place after he was made sikong. According to Emperor Wu's biography in the same work, Jia Chong was made sikong in c.August 272. ([泰始八年]秋七月，以车骑将军贾充为司空。); the month corresponds to 11 Aug to 9 Sep 272 in the Julian calendar. Vol.26 of the same work indicated that by 274, Xiahou He was already Minister of the Household. Thus, the incident must have happened between Aug 272 and 274. Vol.80 of Zizhi Tongjian dated this incident to 276 (2nd year of the Xian'ning era). While Emperor Wu's biography in Book of Jin did record that he was gravely ill in that year, if both Jin Shu and Tongjian were correct, it would mean that Xiahou He was first Minister of the Household in 274, then became Intendant of Henan before becoming Minister of the Household again after the incident.
^(初，帝疾笃，朝廷属意於攸。河南尹夏侯和谓充曰：“卿二女婿，亲疏等耳，立人当立德。”充不答。及是，帝闻之，徙和光禄勋，乃夺充兵权，而位遇无替。) Book of Jin, vol.40
^([咸宁二年]八月...己亥，...司空贾充为太尉，镇军大将军齐王攸为司空。) Jin Shu, vol.03
^Emperor Wu's biography in Book of Jin recorded that Sima You was made da sima, Great General who Stabilizes the East, and overall in charge of military affairs concerning Qingzhou on 28 January 283. ([太康三年]冬十二月甲申，以司空齐王攸为大司马、督青州诸军事，镇东大将军、...) Jin Shu, vol.03. This was also the last entry to mention You before his death in April that year.
^Fang, Xuanling, ed. (648). "列傳第十二" [Historical Biography 12]. 晉書 [Book of Jin] (in Chinese).
^Fang, Xuanling, ed. (648). "帝纪第三" [Chronicles of the Emperor]. 晉書 [Book of Jin] (in Chinese).