World War I (abbreviated as WW-I, WWI, or WW1), also known as the First World War, the Great War, and the War to End All Wars, was a global military conflict which involved most of the world's great powers, assembled in two opposing alliances: the Allies of World War I centred around the Triple Entente and the Central Powers, centred around the Triple Alliance. More than 70 million military personnel were mobilized in one of the largest wars in history. More than 40 million people were killed, making it one of the deadliest conflicts in history. During the conflict, the industrial and scientific capabilities of the main combatants were entirely devoted to the war effort.