2. When Xiang Yu was besieged by Liu Bang's troops, Han Xin, a general of the Han army, deliberately made the soldiers sing the songs of the Chu people in order to demoralize Xiang Yu. Xiang Yu and others can't help but be sad and surprised after hearing Chu songs, and completely lose their fighting spirit.

3. Xiang Yu was surrounded by the Han army led by Han Xin, and fell into a tight encirclement. Now they are facing the desperate situation of running out of ammunition and food, and with the ambush of the Han army on all sides, there is almost no hope for the Chu army to break through. Who would have thought that this time, Han Xin thought of an idea again, which dealt a fatal blow to Xiang Yu's army.

When night falls, the soldiers in Han Xin Camp sing songs of Chu. At this time, Chu songs sounded in all directions, and Xiang Yu was frightened after listening. He heard the songs from his hometown coming from the Han army barracks and mistakenly thought that the Chu army had surrendered to Liu Bang. Hope and fighting spirit in my heart suddenly disappeared by half. Now people are used to using the idiom "besieged on all sides" to describe people's despair and helplessness in desperate situations.