Yuan Zai
Li Kuo's activities as crown prince were not much recorded in the official histories—although, in 778, after Emperor Daizong executed the corrupt chancellor Yuan Zai, he stated to his close associate Li Mi that it was Li Kuo who revealed Yuan's corruption. In 779, when Emperor Daizong fell ill, Li Kuo briefly served as regent, and when Emperor Daizong subsequently died, he succeeded Emperor Daizong (as Emperor Dezong).