English Original
At the end of the Qin Dynasty (221-206 B.C.), the states of Chu and Han fought for control of the country. Xiang Yu, the king of Chu, was besieged at Gaixia by the Han army led by Liu Bang. With little food and few soldiers, Xiang Yu was in a desperate situation. One night, the surrounding Han troops began singing Chu folk songs. Xiang Yu was astonished and said, "Has Liu Bang already conquered all of Chu? How can he have so many Chu people in his army?" He then fled with the remnants of his forces.
This idiom is used metaphorically to describe being in a helpless and critical situation, surrounded by enemies on all sides.
中文翻译
秦朝末年（公元前221-206年），楚汉两国为争夺天下而战。楚王项羽被刘邦率领的汉军围困在垓下。项羽粮草匮乏，兵少将寡，陷入绝境。一天夜里，包围他们的汉军唱起了楚地民歌。项羽闻之大惊，说道：“难道刘邦已经占领了整个楚国？他军中怎么会有这么多楚人？”随后，他便率领残部逃走了。
这个成语用来比喻陷入孤立无援、四面受敌的危急困境。