During the Warring States period (475-221 B.C.), Prince Mengchang of the State of Qi was known for hosting thousands of retainers from all walks of life. He welcomed anyone who came to his door, utilizing the talents of the capable and providing food and lodging even to those with mediocre skills.
Once, Prince Mengchang led his retainers on a diplomatic mission to the State of Qin. King Zhao of Qin, impressed by him, detained him and intended to make him his prime minister. However, persuaded by his advisors that the prince's loyalties would always lie with his homeland of Qi, the king changed his mind. He placed Prince Mengchang and his men under house arrest, plotting to kill them.
In desperation, Prince Mengchang sought help from the king's favorite concubine. She agreed to intervene, but demanded a unique white fox fur coat from Qi as her reward—the very coat Prince Mengchang had already presented to the king. One of his retainers, a skilled burglar who could slip through dog holes, volunteered to retrieve it. Under the cover of moonlight, he evaded guards, infiltrated the palace storeroom, and stole the coat back.
Pleased with the gift, the concubine convinced the king to release Prince Mengchang and even plan a farewell banquet. Fearful of further delays, Prince Mengchang and his men fled eastward that very night. They reached the Hangu Pass at midnight. According to Qin law, the gates opened only at the rooster's crow at dawn. Another retainer, who could perfectly imitate a rooster's crow, saved them. His imitation triggered real roosters to crow, confusing the guards into opening the gates prematurely.
By the time King Zhao discovered the escape at dawn and sent troops in pursuit, Prince Mengchang's group had long since crossed the pass and returned safely to Qi.
This story, recorded in Sima Qian's Historical Records, gave rise to the idiom "the crow of a rooster and the snatch of a dog." It refers to seemingly insignificant skills or the people who possess them, which can prove invaluable in critical situations.