Tensions had been brewing throughout Europe-especially in the troubled Balkan region of southeast Europe-for years before World War I actually broke out. By the time the war was over and the Allied Powers claimed victory, more than 16 million people-soldiers and civilians alike-were dead. Thanks to new military technologies and the horrors of trench warfare, World War I saw unprecedented levels of carnage and destruction.

During the conflict, Germany, Austria-Hungary, Bulgaria and the Ottoman Empire (the Central Powers) fought against Great Britain, France, Russia, Italy, Romania, Japan and the United States (the Allied Powers). World War I, also known as the Great War, began in 1914 after the assassination of Archduke Franz Ferdinand of Austria. His murder catapulted into a war across Europe that lasted until 1918.