sentences:  Later in Emperor Gaozu's reign, Li Shimin was locked in an intense rivalry with his older brother Li Jiancheng the Crown Prince, and Fang and Du often suggested that he act first against Li Jiancheng.As both Li Jiancheng and another brother who supported Li Jiancheng, Li Yuanji the Prince of Qi, feared Fang's and Du's strategic capabilities, they falsely accused both Fang and Du and had them demoted out of Li Shimin's staff.In summer 626, when Li Shimin decided to act against Li Jiancheng and Li Yuanji, however, he summoned Fang and Du to his mansion.