In 219, Guan Yu launched an invasion against Cao Cao, leaving Mi Fang with the defence of the base city in Jiangling, and Shi Ren in Gong'an County. Earlier, Mi Fang had accidentally set some military equipment ablaze, and Guan threatened to dish out harsh punishment should he triumph over Cao Cao. Since then, Mi Fang had been fraught with fear and receiving letters from Sun Quan, who was also a brother-in-law to Liu Bei, and also disgraced by Guan Yu's insolence.