After Emperor Gaozu of Han, Liu Bang, unified the realm, two pressing concerns kept him restless: first, his ministers bickered over merits and rewards, with some already showing signs of rebellion despite his enfeoffment of key contributors as kings, making Liu Bang suspect every official; second, his crown prince appeared weak and unkingly, raising doubts about his ability to shoulder the empire's burden. These worries robbed Liu Bang of peaceful sleep.
In the eleventh year of Emperor Gaozu of Han, Chen Xi and Han Xin successively plotted rebellions, but Liu Bang swiftly quelled the uprisings, and the political situation briefly stabilized.
As Emperor Liu Bang’s health declined, his worry over succession grew. He adored his youngest son, Prince Ruyi of Zhao, born of his beloved consort Lady Qi, and wanted to replace the crown prince. But Lady Lü opposed this fiercely, and veteran advisors like Zhang Liang secretly aided her, protecting the heir. Liu Bang had no choice but to drop the matter for now.
The following autumn, another vassal king, Ying Bu, launched a rebellion. Seeing one meritorious official after another executed, Ying Bu knew that Emperor Liu Bang's suspicions had turned toward him—if he didn't rebel now, when would he? But Liu Bang was ill and planned to send the Crown Prince to lead the army against Ying Bu. This arrangement spelled disaster for the prince: the generals assigned to accompany him were fierce veterans who had conquered the realm alongside Liu Bang himself. A timid prince commanding such formidable men would never earn their loyalty or effort, making victory impossible. Returning without success would seal the prince's doom.
Lü was extremely anxious over this, and with no other choice, went directly to persuade Liu Bang to revoke his order. She tearfully said to him:
The strategist warned, "Ying Bu is a fierce general, skilled in warfare. Most of your commanders were once your equals, and sending the Crown Prince to lead them is like sending a sheep to command wolves—will they obey him? Moreover, if Ying Bu learns you've dispatched the prince, he'll have no fear. I urge you to take the field yourself, even if you must direct the battle from a carriage. Then every general will fight to the fullest. It will be taxing, but far better than sending the prince."
Liu Bang realized that his son was indeed unfit for the task, so he had no choice but to personally lead the army to quell Ying Bu's rebellion.
"The idiom 'Using Sheep to Lead Wolves' means using the weak to command the strong, which inevitably leads to disaster."
Source: *Records of the Grand Historian*, "Biography of the Marquis of Liu"
Meaning of the Idiom: Later, the Chinese idiom "使羊将狼" came to describe using the weak to command the strong, which inevitably leads to disaster.