Yuchi Jiong
In 580, Emperor Xuan died, and his father-in-law Yang Jian seized power as regent. He invited Li to serve as his assistant, and Li pledged loyalty to him. It was at Li's suggestion that Yang immediately made his intentions to eventually take the throne known by assuming particularly elevated titles while serving as regent. When the general Yuchi Jiong rose against Yang at Yecheng, the former Northern Qi capital, Yang particularly entrusted strategic issues with Li, allowing Li to make much of the military decisions during the campaign, which eventually saw Yang defeating Yuchi to affirm his hold on power.