Austria-Hungry wanted to seek revenge against those who assassinated Archduke Franz Ferdinand.
Explanation:
The Archduke of Austria and his wife were assassinated on 28th June 1914 in Sarajevo by Gavrilo Princip. He was one of the six assassins. The reason for the assassination was to get southern Slav provinces ceded from the Austro- Hungarian empire and combined with Yugoslavia. After the assasination, the Austria-Hungry dispatched a list of demand to Serbian government which was known as Black Check. Soon the Austria Hungry declared war. The allies of both countries got involved and soon the whole of Europe was fighting.
