he would yield the territory. Heruo agreed, and the territory became Chen possession. Seeking peace, Northern Zhou offered to return Chen Xu to Chen, and Emperor Wen, pleased, offered to trade the city of Lushan (魯山, in modern Wuhan, Hubei) for Chen Xu's release. Chen Xu returned to Chen in 562 and became a key official in Emperor Wen's administration. Initially, Northern Zhou continued to detain Chen Xu's wife Liu Jingyan and son Chen Shubao, but after further negotiations, Northern Zhou released them as well. Meanwhile, Emperor Wen began to consider the problem of local warlordism—which rendered the modern Jiangxi, Fujian, and large parts of Zhejiang under warlord control and only nominally submissive to him. In spring 562, he tried to summon one of the key warlords, Zhou Di (周迪), to move from his base of Linchuan (臨川, in modern Fuzhou, Jiangxi), to Pencheng (湓城, in modern Jiujiang, Jiangxi). Zhou Di refused, and subsequently unsuccessfully attacked Emperor Wen's general Zhou Fu (周敷). Emperor Wen sent Wu Mingche to attack Zhou Di and sent Hou Andu against another warlord, Liu Yi (留異), who controlled modern southern Zhejiang. By summer 562, Hou had defeated Liu Yi, forcing him to flee to his son-in-law, Chen Baoying (陳寶應), who controlled modern Fujian. Wu, however, was unable to immediately defeat Zhou Di, and Emperor Wen sent Chen Xu to attack Zhou Di instead. In spring 563, Zhou Di's forces collapsed, and he fled to Chen Baoying as well. Chen Baoying, Liu Yi, and Zhou Di regrouped together and resisted Emperor Wen's forces and prepared to counterattack. Zhou soon began a guerrilla campaign, while Chen Baoying and Liu held out at Chen Baoying's headquarters at Jin'an (晉安, in modern Fuzhou, Fujian). Meanwhile, Emperor Wen had become increasingly angry and suspicious of Hou Andu's arrogance and protection of his officers' misdeeds. In summer 563, he arrested Hou and forced him to commit suicide. In summer 564, Zhou Di, after several successful battles, regained some of his following, and soon tricked and assassinated Zhou Fu. However, Emperor Wen's general Zhang Zhaoda (章昭達) was able to capture Jin'an. Chen Baoying and Liu fled but were captured and executed. By fall 565, Emperor Wen's general Cheng Lingxi (程靈洗) was able to defeat Zhou Di, who was subsequently betrayed by his own soldiers and killed. Emperor Wen had by now largely unified his state. In summer 566, Emperor Wen grew ill.