刘武周
After that, Li Shimin beseeched Yuchi Gong to join his force for several times. Yuchi Gong was finally moved by Li Shimin. From others, Yuchi Gong also started to believe that it was not Li Shimin who treated him unfairly in the camp. Eventually, after the death of Liu Wuzhou and Song Jingang, Yuchi Gong surrendered to Li Shimin and became a major general fighting for Tang Dynasty. In the battle of Luo Yang, when Li Shimin was attacked by Shan Xiongxin, it was Yuchi Gong who saved Li Shimin. And when Li Shimin was framed by his brothers Li Jiancheng and Li Yuanji, Yuchi Gong played a big part in proving Li Shimin's innocence. Without Yuchi Gong, Li Shimin would never become the emperor.