When you must serve your country faithfully is a legendary novel written by Feng Menglong, a writer in Ming Dynasty. This novel tells the story of Zhu Jianshen, the emperor of Wenjian in the Ming Dynasty, who was overthrown by the Jingnan War and lived in the south of the Yangtze River. With the help of a group of loyal ministers, he finally revitalized the country and restored the throne.

This novel has high literary and historical value, vividly shows the loyalty spirit of the people at that time, and is of great significance for reflecting the history of the Ming Dynasty and describing the social outlook at that time.

In addition, this novel profoundly reveals the darkness and corruption of the society at that time, and appeals to people to carry forward the wind of loyalty to the monarch and strive to revitalize the country, which has far-reaching educational significance. Therefore, When You Must Serve Your Country Faithfully is regarded as one of Feng Menglong's representative works and a classic in the history of China literature.