Yue Fei was a famous soldier in the Southern Song Dynasty. When he was a child, his family was poor. Yue Fei's mother used branches to write on the beach to teach him and encourage him to take good exercise so that he can do his part for the country in the future. At that time, the nomads from the north often attacked the Central Plains. His mother-in-law encouraged him to serve the country. At that time, Yue Fei hesitated that his mother was left unattended, but her mother-in-law told him that "loyalty and filial piety have never been tolerated since ancient times" and advised Yue Fei to focus on state affairs and not to miss his family.

Before Yue Fei went to join the army, his mother tattooed the words "loyal to the country" on his back. The filial Yue Fei did not dare to forget his mother's lesson, and those four words became the creed that Yue Fei followed all his life.