<a href="https://en.wikipedia.org/wiki/Austria-Hungary" id="mwcQ" rel="mw:WikiLink" title="Austria-Hungary">Austria-Hungary</a> issues a series of demands in an <a href="https://en.wikipedia.org/wiki/July_Crisis" id="mwcg" rel="mw:WikiLink" title="July Crisis">ultimatum</a> to the <a href="https://en.wikipedia.org/wiki/Kingdom_of_Serbia" id="mwcw" rel="mw:WikiLink" title="Kingdom of Serbia">Kingdom of Serbia</a> demanding Serbia to allow the Austrians to determine who <a class="mw-redirect" href="https://en.wikipedia.org/wiki/Assassination_of_Archduke_Franz_Ferdinand_of_Austria" id="mwdA" rel="mw:WikiLink" title="Assassination of Archduke Franz Ferdinand of Austria">assassinated</a> <a href="https://en.wikipedia.org/wiki/Archduke_Franz_Ferdinand_of_Austria" id="mwdQ" rel="mw:WikiLink" title="Archduke Franz Ferdinand of Austria">Archduke Franz Ferdinand</a>. Serbia accepts all but one of those demands and Austria declares war on <a href="https://en.wikipedia.org/wiki/July_28" id="mwdg" rel="mw:WikiLink" title="July 28">July 28</a>.