 Meanwhile, however, Gao Wei's uncle Gao Jie (高湝) the Prince of Rencheng and cousin Gao Xiaoheng (高孝珩) the Prince of Guangning were still at Xindu (信都, in modern Hengshui, Hebei) and resisting Northern Zhou forces.Emperor Wu sent Yuwen Xian to attack Xindu.Yuwen Xian sent a letter from Gao Wei and wrote a letter himself, both trying to persuade Gao Jie to surrender, but Gao Jie refused.