What was the ultimatum of World War I?

The treaty of Versailles was the ultimatitum as it forced the Germans into a complete surrender and crippled their economy and military fighting force
The ultimatum of WWI was the combination of all the request of the Austrians when in dispute with Serbia during the war when invasion was about to begin. It is called the ultimatum because it was the final decision of the Serbs, Become part of Austria or Perish