In 219, Guan Yu led an army to attack Cao Cao's fortress at Fancheng (樊城; present-day Fancheng District, Xiangyang, Hubei), which was defended by Cao Ren. He left behind his subordinates Shi Ren and Mi Fang to defend Gong'an County and Nan Commandery (南郡; around present-day Jingzhou, Hubei) respectively. When Lü Meng heard about that, he wrote to Sun Quan: Sun Quan agreed to Lü Meng's plan and played along by openly approving his request to return to Jianye for medical treatment.