cavalry and ordered him to defend Yan Ford (延津; in present-day Yanjin County, Henan) from the enemy, while he personally led another army to Guandu (官渡; northeast of present-day Zhongmu County, Henan). Around the time, the warlord Liu Bei seized control of Xu Province after killing Che Zhou (), the provincial governor whom Cao Cao had appointed. Cao Cao then led his forces to attack Liu Bei. Yuan Shao concurrently attacked Yan Ford, but Yu Jin managed to hold his position. Later, Yu Jin and Yue Jin led 5,000 infantry and cavalry to attack Yuan Shao's camps along the Yellow River southwest of Yan Ford. They travelled to as far as Ji (汲; southwest of present-day Weihui, Henan) and Huojia (獲嘉; southeast of present-day Huojia County, Henan) counties. They set fire to over 30 enemy camps, killed or captured thousands of enemy soldiers, and forced over 20 of Yuan Shao's officers, including He Mao () and Wang Mo (), into surrendering. Cao Cao then ordered Yu Jin to garrison at Yuanwu County (原武縣; present-day Yuanyang County, Henan). Yu Jin attacked and destroyed Yuan Shao's camp at Dushi Ford (). Yu Jin was promoted to Major-General () for his achievement and was then relocated to Cao Cao's camp at Guandu. During the Battle of Guandu, Yuan Shao's forces piled up earth to form small hills and constructed platforms on top for their archers, who rained arrows on Cao Cao's camp. Cao Cao's forces sustained many casualties and the soldiers were all fearful. Yu Jin firmly defended his positions, fought bravely, and displayed great fervour. He was promoted to Lieutenant-General () after Cao Cao scored a decisive victory over Yuan Shao at Guandu. Suppressing two rebellions Cao Cao continued waging wars against Yuan Shao after the Battle of Guandu and against Yuan Shao's heirs and allies after Yuan Shao died in 202. By 206, after he had seized control of Ji Province (covering parts of present-day southern Hebei) from the Yuans, a minor warlord Chang Xi () who had initially surrendered to him in early 201 rebelled against him. Cao Cao ordered Yu Jin to lead an army to attack Chang Xi. Chang Xi surrendered to Yu Jin, who was an old friend of his. When his subordinates suggested that he send Chang Xi as a prisoner-of-war to Cao Cao and let Cao Cao decide Chang Xi's fate, Yu Jin said: "Aren't