Xu served as Commander of the Nanjing Military Region (1954–74), first under East China Military and Administrative Committee chairman Rao Shushi, and then for ten years with Gang of Four member Zhang Chunqiao as his political commissar (1967–76). This assignment was the single longest tenure of any Military Region commander on record. Among his deputies during the 1960s were future regional leaders Sung Shilun, Wang Bicheng and Tan Qilong, As the armed forces were called in to restore administrative control, he became Chairman of the Jiangsu Province Revolutionary Committee (1968–74) and CCP First Secretary (1970–74). In the long-delayed military region reshuffle initiated under Deng Xiaoping, Xu was rotated to command the Guangzhou MR (1974–80). Xu and political commissar Wei Guoqing provided protection for Deng Xiaoping in 1976, when the future paramount leader was purged by the Gang of Four following the death of Zhou Enlai. Xu was also commander in chief for the Chinese forces in the Sino-Vietnamese War in 1979.