In January 544, Lý Bôn proclaimed himself emperor and named his small state Vạn Xuân. In winter 544, Xiao Ying died, and initially, Chen started escorting Xiao Ying's casket back to Jiankang for burial. On the way, while he was still at Dayu Mountain (大庾嶺, on the borders of modern Jiangxi and Guangdong), he made a rendezvous with the new governor of Giao Châu Province, Yang Piao (楊瞟), and another nephew of Emperor Wu's, Xiao Bo (蕭勃), to attack Lý Bôn. Xiao Bao did not want to set out on the campaign, and therefore tried to persuade Yang not to advance. Chen persuaded Yang otherwise, and in spring 545, Yang, with Chen as his lieutenant, attacked Lý Bôn, defeating him and forcing him to flee into the mountains and conduct guerilla warfare instead. In 548, Lý Bôn died of illness, and when Lý Bôn's brother Lý Thiên Bảo succeeded him and attacked Ái Province (愛州, around modern Thanh Hóa Province, Vietnam), Chen defeated Lý Thiên Bảo. Emperor Wu made Chen the governor of Gaoyao Commandery (高要, Chen Zhaoqing, Guangdong) as well as the commander of the forces of the surrounding commanderies.
