李愬
It was said that Li Su was full of strategies and capable in horsemanship and archery. In 816, during the reign of Emperor Dezong's grandson Emperor Xianzong, imperial troops were conducting a campaign against the warlord Wu Yuanji, who controlled Zhangyi Circuit (彰義, headquartered in modern Zhumadian, Henan)) without imperial approval, two successive imperial generals put in command of nearby Tangsuideng Circuit (唐隨鄧, headquartered in modern Zhumadian) — Gao Xiayu () and Yuan Zi — had suffered defeats by Zhangyi troops. Li Su volunteered to serve in the campaign, and the chancellor Li Fengji also knew of Li Su's abilities, and therefore recommended him. Emperor Xianzong thus made Li Su the military governor ("Jiedushi") of Tangsuideng Circuit, as well as the prefect of its capital Tang Prefecture (), replacing Yuan.