In the winter of 208–209, Gan Ning fought in the Battle of Red Cliffs under Zhou Yu's command against the forces of Cao Cao, and defeated the enemy at Wulin (烏林). He also participated in the subsequent Battle of Jiangling. Sun Quan's forces, led by Zhou Yu, attacked Cao Cao's general Cao Ren at Nan Commandery (南郡; around present-day Jiangling County, Hubei) but were unable to conquer the city. Gan Ning suggested that he lead a separate force to capture Yiling (夷陵; around present-day Yichang, Hubei). He had only a few hundred soldiers with him when he reached Yiling but the strength of his army increased to around 1,000 after he recruited some men in the area. Cao Ren sent 5,000 to 6,000 troops to besiege Gan Ning at Yiling. Cao Ren's men built high towers, from which they rained arrows upon Yiling. Gan Ning's men were terrified but their commander remained calm. He sent a messenger to request aid from Zhou Yu, who heeded Lü Meng's plan and led reinforcements to help Gan Ning while leaving behind Ling Tong to defend their position. Zhou Yu, Lü Meng and the others succeeded in lifting the siege at Yiling, while Ling Tong managed to hold his ground well for that period of time. Eventually, Cao Ren was ordered to abandon Nan Commandery because the prolonged war had drained much manpower and resources on Cao Cao's side, and this resulted in the capture of the commandery by Sun Quan's forces.