📅 On This Day in Military History

July 23

1 event across history

⚔️📍 Vienna, Austria1914

Austria-Hungary's Ultimatum to Serbia — WWI Countdown Begins

Austria-Hungary issued a 48-hour ultimatum to Serbia with 15 deliberately unacceptable demands following the assassination of Archduke Franz Ferdinand. Serbia accepted all but two demands; Austria declared war anyway.

The ultimatum to Serbia triggered the alliance system that turned a Balkan crisis into World War I, killing 20 million people within four years.

Outcome

Serbia accepts most demands; Austria declares war; WWI begins