World War I By julob Jun 28, 1914 Archduke Ferdinand is assassinated Aug 9, 1914 President Wilson issues a proclamation of neutrality in the European war 1915 German U-boat sinks the Lusitania 1916 Jeannette Rankin becomes the first woman elected to Congress 1917 The US declares war on Germany 1918 Germany agrees to an armistice ending WWI 1919 The US senate refuses to approve the Treaty of Versailles