In 547, the Eastern Wei general Hou Jing, in a conflict with the new regent Gao Cheng, surrendered the 13 provinces (the region between the Yellow River and the Huai River) to Liang, seeking aid from Liang. However, both Xiao Gang's cousin Xiao Yuanming the Marquess of Zhenyang, and Hou himself, were defeated by the Eastern Wei general Murong Shaozong (). Xiao Yuanming was captured, while Hou fled and, surprising the Liang governor of Southern Yu Province (南豫州, modern central Anhui), Wei An (), seized the key city Shouyang (壽陽, in modern Lu'an, Anhui), the capital of Southern Yu Province. Instead of punishing Hou, however, Emperor Wu allowed him to serve as the governor of Southern Yu Province. It is unclear whether Xiao Gang was involved in making these decisions, but he was clearly informed about them, as he revealed these decisions to his assistant He Jingrong ().