Description & Facts: The First World War, was a global military conflict which took place primarily in Europe from 1914 to 1918. Over 40 million casualties resulted, including approximately 20 million military and civilian deaths. The immediate cause of the war was the June 28, 1914 assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, by Gavrilo Princip, a Bosnian Serb citizen of Austria-Hungary. The retaliation by Austria-Hungary against Serbia activated a series of alliances that set off a chain reaction of war declarations. Within a month, much of Europe was in a state of open warfare. The war was propagated by two major alliances. The Entente Powers initially consisted of France, the United Kingdom, Russia and their associated empires and dependencies. Numerous other states joined these allies, most notably Italy in April, 1915, and the United States in April, 1917. The Ottoman Empire joined the Central Powers in October, 1914, followed a year later by Bulgaria. By the conclusion of the war, only The Netherlands, Switzerland, Spain and the Scandinavian nations remained officially neutral among the European countries, though many of those provided financial and material support to one side or the other. The fighting of the war mostly took place along several fronts, that broadly encircled the European continent. The Western Front was marked by a system of trenches and fortifications separated by an area known as no man's land. These fortifications stretched 475