The political vacuum left by the deposed Qin Dynasty was filled by self-styled petty princes whose power had expanded during the war, to the extent that they claimed relative independence from each other along with a fair share of the spoils. In 206 BC Xiang Yu, the commander-in-chief of the allied forces, took over authority to officially recognize this regressive feudalism by legitimizing allies' titles to princedoms or dukedoms. Xiang Yu proclaimed himself "Xi Chu Ba Wang," or the Grand King of Western Chu.
With the seat of his government in Pengcheng (today's Xuzhou, Jiangsu Province). Liu Bang was among the 18 warlords whom Xiang Yu made princes; he was assigned the territories of Ba, Shu and Hanzhong. The same year saw the beginning of discord between Xiang Yu and Liu Bang vying for supremacy. The ensuing war went on for four years. In 202 BC, Liu Bang chased Xiang Yu to Guling (south of today's Taikang, Henan Province). He was joined by Han Xin, Ying Bu and Peng Yue, as they besieged Xiang Yu in Gaixia. Xiang Yu was outnumbered, yet he refused to go down easily. He still had the same elite troops he had possessed under his command from the time he had risen from his home state of Chu. Now they were cornered but they were set to fight to their last breath. Seeing that force could not break him, Zhang Liang resorted to craft. He had his men sing the folksongs of Chu State.
The psychological warfare proved to be effective. Folksongs from their homeland distressed Xiang Yu's soldiers so severely that they no longer wanted to fight but abandoned their posts. Even Xiang Bo left his nephew for Zhang Liang. Xiang Yu was aghast when he heard the songs, which to him to mean that Liu Bang had taken his home state and drafted soldiers from there.