World War I, also known as the First World War, the Great War, and The War to End All Wars, was a global war which took place primarily in Europe from 1914 to 1918. Over 40 million casualties resulted, including approximately 20 million military and civilian deaths. Over 60 million European soldiers were mobilized from 1914 to 1918. 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 and member of the Black Hand. The retaliation by Austria-Hungary against the Kingdom of 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 ended by several treaties, most notably the Treaty of Versailles, signed on 28 June 1919, though the Allied powers had an armistice with Germany in place since 11 November 1918. One of the most striking results of the war was a large redrawing of the map of Europe.