capital Yecheng. 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. When the official Cai Jingli (蔡景歷) warned otherwise, he was so displeased that he demoted Cai to the post of a commandery governor. In spring 578, the Northern Zhou general Wang Gui (王軌) thoroughly crushed Wu, capturing him. Regretting his actions, Emperor Xuan recalled Cai to the capital. With the people's hearts shaken by the great defeat, in fall 578, Emperor Xuan held a ceremony in which the officials reaffirmed their loyalty to the state. In winter 579, Emperor Xuan of Northern Zhou (Emperor Wu's son and successor) launched an attack on Chen, commanded by the general Wei Xiaokuan. Chen's Emperor Xuan mobilized his troops to resist. However, Chen forces could not stand against Northern Zhou's attacks, and all of the cities that they had captured from Northern Qi previously quickly fell. By new year 580, nearly all of the territory north of the Yangtze had fallen to Northern Zhou, leading to a large wave of refugees who fled across the Yangtze to Chen territory. In summer 580, Northern Zhou's Emperor Xuan died suddenly, and his father-in-law Yang Jian seized power as regent. The generals Yuchi Jiong rose against Yang, and he was joined by the generals Sima Xiaonan (司馬消難) and Wang Qian (王謙). Sima, the governor of Xun Province (勛州, roughly modern Xiaogan, Hubei) and the nine surrounding provinces, soon surrendered to Chen, seeking Chen aid. Emperor Xuan sent the generals Fan Yi (樊毅), Ren Zhong (任忠), and Chen Huiji (陳慧紀) to attack Northern Zhou's southern provinces to aid Sima, whom he created the Duke of Sui. However, Wei Xiaokuan quickly defeated Yuchi, forcing Yuchi to commit suicide, and Sima's own forces collapsed. He was forced to flee to Chen territory, and all of the territory he controlled was retained by Northern Zhou. (Yang Jian soon seized the throne in spring 581, ending Northern Zhou and establishing Sui Dynasty) In spring 582, Emperor Xuan died. After a failed