The outbreak of World War I By lyang1 Apr 5, 1914 Germany declared war on Russia Jun 28, 1914 Archduke Franz Ferdinand assassinated in Sarajevo Jul 28, 1914 Austria declared war on Serbia Jul 28, 1914 Russia Mobilised Aug 2, 1914 Germany demanded access through Belgium to fight France Aug 3, 1914 France mobilised in support of Russia Aug 3, 1914 Germany declared war on France and thus invaded Belgium Aug 4, 1914 Britain as ally to Belgium, declared war on Germany Sep 5, 1914 France mobilised in support of Russia