The early 20th century was a time of restlessness and unrest. Since the emergence of industrial civilization represented by machines and metropolises, the colonial powers and their interest groups have begun a new world-wide struggle. The old colonial empires of Britain, France, Russia, and emerging countries such as Germany, Japan, and the United States had irreconcilable conflicts in their competition for resources and colonies. At the same time, the periodic economic crises in capitalist countries and the sharpness of class contradictions also made the governance of various countries unstable. Therefore, they expanded their armies, prepared for war, and looked for alliances in an attempt to alleviate domestic conflicts through foreign wars.
