On June 28, 1914, Archduke Franz Ferdinand of Austria, the heir to the Austro-Hungarian throne, was assassinated in Sarajevo, the provincial capital of Bosnia-Herzegovina (formally annexed by Austria-Hungary in 1908).
Gavrilo Princip, a Bosnian Serb nationalist, fired the fatal shots. The assassination was the culmination of a series of events that had been building up tension between Austria-Hungary and Serbia for several years.
The assassination of Franz Ferdinand was the spark that set off a chain of events that led to the outbreak of World War I.