The world was shaken in 1917, when a socialist revolution swept through czarist Russia, the largest nation in the world. Much of the ideology for the revolution to establish a Chinese republic was developed by Sun Yixian, eventually honoured as the Father of the Chinese Republic. Mao Zedong realized that the sudden collapse of pre-revolutionary governmental authority and coercive capability that provided a unique opportunity for Russian revolutionaries at the close of First World War was unlikely to occur in China. Mao also extracted from his knowledge of military conflicts the concept of people's war and adapted it to the revolutionary struggle in China. China's relative ethnic homogeneity facilitated the mobilization of large numbers into periodic peasant rebellions and later into the peasant-based revolution of the twentieth century. Poverty and natural hardships in the countryside constituted a continuing source of mass frustration that would eventually combine with other critical factors to bring about a sweeping peasant-based socioeconomic revolution.