Timeline of World War I By emvee Jun 18, 1914 Assassination of Franz Ferdinand Archduke Franz Ferdinand heir to the throne of the Austro-Hungarian Empire, and his wife are assassinated in Sarajevo. Jul 28, 1914 Austria-Hungary declares war on Serbia. Aug 1, 1914 Germany declares war on Russia Aug 3, 1914 Germany declares war on France Aug 6, 1914 Austria-Hungary declares war on Russia May 7, 1915 German U-boat sinks RMS Lusitania, killing 1,198 civilians Dec 18, 1916 Battle of Verdun, longest battle, 1 million casualties Apr 6, 1917 US enter war Nov 11, 1918 The war ends, Germany and Allies sign Armistice