Cao. From that point on, although Yuan Shao continued to remain as a major power player, he could no longer challenge Cao Cao's growing supremacy. The latter destroyed the defeated the remaining Yuan troops south of the Yellow River in the Battle of Cangting (201), concluding the Guandu campaign. Fall of the Yuan power bloc (202–207) After Yuan Shao died of illness in 202, a succession struggle developed between his oldest son Yuan Tan and third son Yuan Shang. Several years before Yuan Shao's death, based on the traditional order of succession, Yuan Tan should have been designated as the heir apparent, but as Yuan Shao's wife Lady Liu favoured Yuan Shang, Yuan Shao had Yuan Tan posthumously adopted by the latter's uncle, Yuan Cheng (袁成). Yuan Shao then divided his territories between his sons and nephew Gao Gan, ostensibly so that he could determine their abilities. His base of Ji Province was given to Yuan Shang, Yuan Tan controlled Qing Province, Yuan Xi governed You Province, and Gao Gan ruled Bing Province. On his deathbed, Yuan Shao did not leave any explicit instruction as to who should succeed him. Of Yuan Shao's followers, Pang Ji and Shen Pei supported Yuan Shang, while Xin Ping and Guo Tu favoured Yuan Tan. After Yuan Shao's death, most of his subordinates initially wanted Yuan Tan to be their new lord since he was the oldest son. However, Shen Pei and Peng Ji forged a will, naming Yuan Shang as the successor. Yuan Tan was furious and mobilized his forces under the pretext of attacking Cao Cao, drawing Cao's attention, and Cao preemptively retaliated. Yuan Shang came to his oldest brother's aid, and they fought inconclusively against Cao Cao in the Battle of Liyang. In 203, Cao Cao scored a major victory over the Yuans, who retreated to Ji Province's capital, Ye (鄴). Cao Cao then planned to besiege Ye, but later withdrew his forces after heeding Guo Jia's advice. Guo Jia reasoned that if Cao Cao pressured the Yuans, they might unite against a common enemy; however, if Cao Cao retreated, the disgruntled Yuan brothers would start fighting among themselves. Guo Jia's prediction came true later when Yuan Tan, still bearing a grudge against Yuan Shang for receiving a larger inheritance, attacked Yuan Shang, but his forces in Qing Province defected to Yuan Shang. Yuan Tan fled to Pingyuan (in present-day Dezhou,