World war i was considered to truly be a world war because of the amount of people and nations that got involved in the war. the main combatants were britain, france, and russia on the allied side and germany, austria-hungary, and the ottoman empire on the central powers side. not only were the nations involved but all of the resources of the european colonial empires were brought to bear. smaller nations in europe got involved on either side due to a complex system of alliances that existed in europe before the war. as the war wore on, even more nations were dragged in. the reasons varied. some, like the united states, got involved by trading with one side. others, like italy and japan, opportunistically jumped in to make territorial gains. by the end of the war, most of the world was involved-making it truly a world war. given that the world was at war, how were the central powers defeated?