Li Su, the good-for-nothing prince hated by everyone in the capital like a dog, was driven out of the court and enfeoffed to the barren Lingnan Prefecture to fend for himself. Three years later, Emperor Qian showed mercy and permitted all vassal kings to enter the capital to pay New Year's respects. Leading one thousand personal guards, each equipped with a horse, Li Su rushed to the walls of the capital city just as thirty thousand Tartar cavalry were besieging the city. High officials of the court and Emperor Qian stood on the city tower, preparing to send someone to negotiate and accept a humiliating treaty, when they saw Li Su lead his thousand personal guards to slaughter into the enemy formation! Emperor Qian directly cried out, is this still my good-for-nothing imperial son? This is my qilin son.