World War I By beautifulxdangel Period: Jan 1, 1900 to Dec 31, 1905 1900 Period: Jan 1, 1905 to Dec 31, 1910 1900 Sep 26, 1905 Schlieffen Plan Developed Period: Jan 1, 1910 to Dec 31, 1915 1900 Period: Jan 1, 1915 to Dec 31, 1920 1900 Period: May 1, 1920 to Dec 31, 1925 1900 Period: Jan 1, 1925 to May 7, 1930 1900