World war 1 By Jhowaru May 28, 1914 Assasination of archduke franz Ferdinand Aug 14, 1914 Germany invades Germany invades Belgium May 7, 1915 Lusitania German u boat sinks the Lusitania Sep 15, 1916 First tank British use tanks for the first time in battle Feb 25, 1917 Zimmermann telegram Telegram trying to get Mexico to side with Germany Apr 6, 1917 USA United States enters war