World War I, also known as the First World War or the Great War, was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918 and was contemporaneously described as "the war to end all wars." It led to the mobilization of more than 70 million military personnel, including 60 million Europeans, making it one of the largest wars in history, and it was also one of the deadliest conflicts in history, with an estimated nine million combatant and seven million civilian deaths as a direct outcome of the war, while resulting genocides and the 1918 influenza pandemic caused another 50 to 100 million deaths worldwide. The conflict began after Archduke Franz Ferdinand, prince of the Austria-Hungary throne, was assassinated in Sarajevo, followed by Austria-Hungary's demands on Serbia, declarations of war by Austria-Hungary on Serbia, Germany on Russia and France, and Britain on Germany. Major events included the Battle of Tannenberg, the First Battle of the Marne, the beginning of four years of trench warfare, the First Battle of Ypres, the Ottoman Empire's entry into the war, German submarine attacks on Allied merchant ships around Britain, the Gallipoli campaign, the sinking of the Lusitania, the Battle of Verdun, the Battle of the Somme, the Russian Revolution, the removal of Tsar Nicholas II, the United States entering the war, the Bolsheviks led by Lenin overthrowing the Russian government, Russia agreeing to peace and leaving the war, President Woodrow Wilson's Fourteen Points, Germany's Spring Offensive, the armistice that ended fighting at 11am on the 11th day of the 11th month in 1918, and the Treaty of Versailles signed by Germany in 1919.