WW1 timeline By Daniel syed Jun 28, 1914 Francis Ferdinand assassinated at Sarajevo Jul 5, 1914 Kaiser William II promised German support for Austria against Serbia Aug 1, 1914 Germany declared war on Russia Aug 4, 1914 Britain declared war on Germany Aug 26, 1914 The BEF started its retreat from Mons. Germany invaded France. Dec 12, 1914 Battle of the Marne started