In the final years of the Chin dynasty, China was in turm oil, with many ambitious people fighting for control of the Central Plains. When the fighting was over, two people were left - Liou Bang and Siang Yu. The two cooperated, overthrew the Chin government and divided up China. But both of them wanted to become emperor, and still often fought wars between themselves.
Several years later, Shiang Yu suggested that they divide China up, each take half, and each promise not to invade the others territory anymore. Liou Bang agreed, because he was afraid of Shiang Yu, but secretly began to strengthen his forces. Finally he attacked Shiang Yu, drove him to Gai Shia, and surrounded him. Although Shiang Yu was in imminent danger, Liou Bang was still afraid, and didnt dare to hastily go in and capture him. So he ordered his troops to begin singing Chu folksongs, in order to arouse feelings of homesickness among Shiang Yus troops. That night Shiang Yu heard all around him familiar songs of his homeland. He felt discouraged, and his troops no longer had the heart to fight. In the end, this hero committed suicide at Wujiang.
Today, that idiom refers to being in a difficult situation, opposed by many people.