n late June 1914, Archduke Franz Ferdinand of Austria was assassinated by a Serbian nationalist in Sarajevo, Bosnia. An escalation of threats and mobilization orders followed the incident, leading by mid-August to the outbreak of World War I, which pitted Germany, Austria-Hungary and the Ottoman Empire (the so-called Central Powers) against Great Britain, France, Russia, Italy and Japan (the Allied Powers). The Allies were joined after 1917 by the United States. The four years of the Great War–as it was then known–saw unprecedented levels of carnage and destruction, thanks to grueling trench warfare and the introduction of modern weaponry such as machine guns, tanks and chemical weapons. By the time World War I ended in the defeat of the Central Powers in November 1918, more than 9 million soldiers had been killed and 21 million more wounded.

WORLD WAR I BEGINS (1914)
Though tensions had been brewing in Europe–and especially in the troubled Balkan region–for years before conflict actually broke out, the spark that ignited World War I was struck in Sarajevo, Bosnia, where Archduke Franz Ferdinand, nephew of Emperor Franz Josef and heir to the Austro-Hungarian Empire, was shot to death along with his wife by the Serbian nationalist Gavrilo Princip on June 28, 1914. The assassination of Franz Ferdinand and Sophie set off a rapid chain of events: Austria-Hungary, like many in countries around the world, blamed the Serbian government for the attack and hoped to use the incident as justification for settling the question of Slavic nationalism once and for all. As Russia supported Serbia, Austria-Hungary waited to declare war until its leaders received assurances from German leader Kaiser Wilhelm II that Germany would support their cause in the event of a Russian intervention, which would likely involve Russia’s ally, France, and possibly Great Britain as well.
On July