Yan Fu put forward the slogan of "saving the nation for survival". 1895 After treaty of shimonoseki signed the Treaty of Disgracing the Rights and the Country, Yan Fu shouted the slogan of "saving the nation and saving the country". At the same time, the "Theory of Natural Evolution" was published, in which the fittest survive and the unsuitable are eliminated, and the importance of saving the nation and learning from foreigners to control foreigners was further expounded.

1894, the Sino-Japanese Sino-Japanese War of 1894 broke out, the Beiyang Navy was completely annihilated, and Qiang Bing, a rich country painstakingly managed by the Westernization School, went bankrupt. The sacrifice of former classmates and friends and the further oppression of the nation by the great powers deeply hurt Yan Fu's heart. Without strong political power, Yan Fu tried to realize his ideal of saving the country in another way.