Yu Si 虞汜

According to the record of Yu Fan in Records of Wu 12, Yu Fan's courtesy name was Zhongxiang and he was a man of Yuyao County in Kuaiji Commandery. Because he repeatedly remonstrated with Sun Quan to his face and his nature did not fit in with the world, he was moved to Jing County in Danyang Commandery, and later, as Sun Quan's anger accumulated, he was moved to Jiao Province. Yu Fan lived in the south for more than ten years and died at the age of seventy; he was brought back and buried in the old family graveyard, and his wife and children were allowed to return. Records, Wu 12 §2 · 7 · 13–14

Yu Fan had eleven sons, of whom the fourth son, Yu Si, was the best known. At the beginning of the Yong'an era Yu Si went from Gentleman of the Personnel Bureau to Palace Cavalier Regular Attendant. Of Yu Si's younger brothers, Yu Zhong was Administrator of Yidu; Yu Song, after being Colonel of the Yue Cavalry, was promoted several times to become Commandant of Justice and Administrator of Xiangdong and of Hejian; and Yu Bing served as Commandant of Justice, Master of Writing and Administrator of Jiyin. Records, Wu 12 §16

According to the record of Wang Fan in Records of Wu 20, when Sun Xiu came to the throne, Wang Fan, together with He Shao (賀邵), Xue Ying and Yu Si, all became Palace Cavalier Regular Attendants, and all were additionally given the post of Chief Commandant of Escort Cavalry. Opinion at the time regarded them as men of integrity. Records, Wu 20 §2

According to the Biographies of the Three Successor Rulers in Records of Wu 3, in the 3rd year of Baoding (268) under Sun Hao, Wu sent the Inspector of Jiao Province Liu Jun (劉俊), the Commander of the Front Division Xiu Ze and others to invade Jiaozhi, but they were defeated by the Jin general Mao Jiong and others and all died, and their soldiers scattered and returned to Hepu. In the 1st year of Jianheng (269) Wu sent the Army Supervisor Yu Si, the General Who Overawes the South Xue Xu and the Administrator of Cangwu Tao Huang by the Jing Province route, and the Army Supervisor Li Xu and the Army Inspector Xu Cun by the sea route from Jian'an, all to advance to Hepu and attack Jiaozhi. Records, Wu 3 §60–61

In the 2nd year of Jianheng (270) Li Xu, claiming that the Jian'an route was not passable, killed the guiding general Feng Fei and led his troops back, and Li Xu and Xu Cun were executed together with their families. In the 3rd year of Jianheng (271) Yu Si and Tao Huang crushed Jiaozhi and captured and killed the commanders Jin had installed there, and Jiuzhen and Rinan both returned to allegiance. Wu divided Jiaozhi to establish Xinchang Commandery, and when the generals crushed Fuyan, it established Wuping Commandery. Records, Wu 3 §62–63

The record of Yu Fan says that Yu Si later became Army Supervisor Envoy and died of illness while campaigning against Fuyan. Chen Shou's main text does not state the year of his death or his age. Records, Wu 12 §16Records, Wu 3 §63

In his assessment in Records of Wu 12, Chen Shou said that it was only natural that Yu Fan, like the wildly upright men of old, could hardly escape misfortune in a declining age, but that Sun Quan's inability to tolerate him was not a sign of a generous spirit. The assessment does not discuss Yu Si separately. Records, Wu 12 §89