Sima Yue
Sima Yue decided to act against Sima Yong. In fall 305, he declared a rebellion with the stated intention of returning Emperor Hui to Luoyang. The warlords of the empire were forced to take sides, but eventually they generally fell into line behind Sima Yue because they were disgusted with Zhang's cruelty. The battles were initially largely indecisive, but early 306, after Sima Yue had some minor victories over Sima Yong's forces, Sima Yong panicked and killed Zhang, seeking peace with Sima Yue. Sima Yue refused, and by later that year was able to force Sima Yong to abandon both Emperor Hui and Chang'an. Sima Yue welcomed Emperor Hui back to the capital Luoyang. Early in 307, Emperor Hui was poisoned to death, and historians generally agreed that the poisoning was done at Sima Yue's orders, but the motive was unclear. Crown Prince Chi ascended to the throne as Emperor Huai.