World War I Timeline By bubblefish Jun 28, 1914 Assassination of Archduke Ferdinand Jul 28, 1914 Austria-Hungary declares war on Serbia to kick off WWI Sep 6, 1914 Battle of the Marne Oct 19, 1914 The Race to the Sea May 7, 1915 Sinking of the RMS Lusitania; Germany promises not to target passenger liners; anti-German sentiment begins to build Feb 1, 1917 Germany resumes USW Dec 17, 1917 Germany knocks Russia out of the war (Treaty of Brest-Litovsk) This extended from late 1917 to early 1918 Mar 17, 1918 "Spring Offensive" - Last major German offensive Period: Sep 17, 1918 to Nov 17, 1918 Meuse-Argonne Offensive; final Allied offensive leading to German surrender; also largest American battle of WWI Nov 11, 1918 Armistice ends hostilities at 11:00am, 11/11/1918