Assassination of Archduke Franz Ferdinand

Serbian nationalism was developing strong in the turbulent Balkan Region in the early twentieth century, and the ascent of a new king more favorable to the Russians in 1903 threatened Austria-Hungary. This sparked animosity between the neighbors, culminating in the "great war" of 1906, during which trade frontiers were closed, harming Serbian pig exports to Austria-Hungary in particular. Serbia's nationalist ambitions in Bosnia, a trade route to the Adriatic Sea, grew as a result of the move. The situation deteriorated further in 1908, when Austria-Hungary proclaimed the annexation of Bosnia and Herzegovina, which had previously been under the Ottoman Empire's control.

Gavrilo Princip, one of a group of six assassins (five Serbs and one Bosniak) co-ordinated by Danilo Ili, a Bosnian Serb and a member of the Black Hand secret society, kills Archduke Franz Ferdinand, the heir presumptive to the Austro-Hungarian throne, and his wife, Sophie, Duchess of Hohenberg, with two gunshots in Sarajevo on June 28, 1914.

The assassination was noteworthy because it was considered as an existential threat by Austria-Hungary, and hence as a casus belli with Serbia. Emperor Franz Josef was 84 years old at the time, and the assassination of his successor, so close to handing over the throne, was seen as a direct challenge to the empire. Many Austrian ministers, particularly Berchtold, think that the crime must be avenged. Furthermore, the Archduke had previously been a strong advocate for peace, but he was suddenly absent from the debates. The assassination sparked the July Crisis, which escalated a local struggle into a European and then a global conflict. So, we can say that this is one of the major causes of World War I.