周世宗
Zhao Kuangyin initially served in the Later Han military but he subsequently defected to serve under Chai Rong, emperor of Later Zhou, an enemy of the Later Han. He also persuaded his father, a Later Han general, to serve Chai Rong, thus contributing to the decline and collapse of the Later Han. Having gained Chai Rong's trust, Zhao Kuangyin was assigned as guardian to Chai Rong's seven-year-old son, Guo Zongxun, before Chai's death.