WORLD HISTORY

Detailed explanation-1: -Austria-Hungary declares war on Serbia, beginning World War I.

Detailed explanation-2: -The spark that set off World War I came on June 28, 1914, when a young Serbian patriot shot and killed Archduke Franz Ferdinand, the heir to the Austro-Hungarian Empire (Austria), in the city of Sarajevo. The assassin was a supporter of the Kingdom of Serbia, and within a month the Austrian army invaded Serbia.

Detailed explanation-3: -A month after the assassination of Archduke Franz Ferdinand and his wife Sophie on July 28, 1914, the Austro-Hungarian government declares war on Serbia. Immediately, and within a period of six days, European countries declare war upon one another.

Detailed explanation-4: -The war was started by the leaders of Germany and Austria-Hungary. Vienna seized the opportunity presented by the assassination of the archduke to attempt to destroy its Balkan rival Serbia.