[10] This friendship turned out to be a double-edged sword; when Sima Yao was removed from his post on 12 May,[11] Mao was also implicated and forced to his fiefdom.
[12] While at his fiefdom, Sima Mao was recorded to engage in business; he was also extravagant and enjoyed privileges beyond what his rank entitled him to.
[15] Sima Mao's fortunes again turned in c.November, when his friend Yao was recalled to the Jin court; he was made General who Pacifies the East and Chief Controller of Xuzhou, and sent to garrison Xiapi.
He cited that Yong's general Zhang Fang had forcibly moved Emperor Hui to Chang'an and aimed to bring him back to Luoyang.
[17] In Ji province, Sima Xiao received some elite Xianbei and Wuhuan cavalry forces from Wang Jun.
Sima Mao was made Prince of Jingling during the reign of Emperor Huai, although the exact date or year is unknown.
[19][20] However, Sima Yue's death led to a further weakening of Jin imperial authority, which accumulated to the Disaster of Yongjia in July, where Mao was killed.