Answer:
On July 28, 1914, one month to the day after Archduke Franz Ferdinand of Austria and his wife were killed by a Serbian nationalist in Sarajevo, Austria-Hungary declares war on Serbia
Explanation:
Serbia annexed much of the former Austrian holdings in the Balkans to become the Kingdom of Serbs, Croats and Slovenes, later the Kingdom of Yugoslavia. Austria was eventually annexed by Germany, ending its separate foreign relations.
