 Soon, he captured the Northern Qi emperor Gao Wei and annexed most of Northern Qi's territory by spring 577.Oddly enough, Emperor Xuan believed that he could seize part of Northern Qi territory after Northern Zhou's victory, and he sent Wu Mingche to again advance north.In winter 577, Wu put Pengcheng (彭城, in modern Xuzhou, Jiangsu) under siege, and Emperor Xuan was confident that Wu would soon be able to capture the region south of the Yellow River.