窦建德
In 621, Li Shimin put Luoyang under siege and, after defeating Wang's ally Dou Jiande the Prince of Xia, forced Wang to surrender. Li Shimin spared Wang, but executed a number of his high-level officials. Du Yan was initially set to be executed. Du Chuke asked Du Ruhui to intercede on Du Yan's behalf, and Du Ruhui initially refused. Du Chuke, however, pointed out that while Du Yan was responsible for their older brother's death, he was an uncle. Du Ruhui relented and pleaded with Li Shimin on Du Yan's behalf, and Du Yan was spared.