Li Yuanji
Li Yuan made Li Jiancheng and Li Shimin both key generals, but the younger Li Yuanji was not, initially, although Li Yuan created him the Duke of Guzang. When Li Yuan subsequently began his campaign toward Chang'an, he left Li Yuanji in charge at Taiyuan. Later that year, after he captured Chang'an and declared Yang You emperor (as Emperor Gong) but kept power for himself as regent, he created Li Yuanji the Duke of Qi and put him in charge of the 15 commanderies around Taiyuan.