The ultimatum stated that the Serbian government must accept an Austro-Hungarian inquiry into the Archduke's assassination. Serbia was also required to suppress anti-Austrian propaganda and attempt to eliminate its terrorist organisations. Serbia accepted all terms but refused to give Austria Hungary the power of an inquiry into the assassination. Austria Hungary broke off diplomatic relations with Serbia as a result, and would declare war three days later on July 28th.
Editors. "Austro-Hungarian ultimatum to Serbia". The Literary Encyclopedia. First published 01 March 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=12192, accessed 28 March 2017.]