World War I, also known as "The War to End All Wars," was a global military conflict fought mostly in Europe from 1914 to 1918 that left millions dead and shaped the modern world. The Allied Powers, led by France, Russia, and the British Empire and later joined by Italy and the United States, defeated the Central Powers of Austria-Hungary, the German Empire, Bulgaria, and the Ottoman Empire. Much of the fighting took place along the Western Front in a system of manned trenches and fortifications called "no man's land," and hostilities also occurred for the first time in the air and through submarine warfare. The war ended with the signing of the Armistice of November 11, 1918, and total American casualties were 321,000.