World War I was sparked by the assassination of Franz Ferdinand, the Austrian heir to the throne, by a Bosnian Serb. This event triggered an international crisis that led to the outbreak of the Great War.
The final trigger for war would be the pent-up pressure of nationalism within the polyglot Austro-Hungarian Empire. Various nationalist groupings were making their plans. Collectively, they were highly motivated conspirators and in June 1914 they were given their chance to change the world. The culmination of months of plotting was the assassination of the Archduke of Austria, Franz Ferdinand, in Sarajevo on the 28th of June 1914. Franz Ferdinand was the heir presumptive of the Austro-Hungarian throne. As such, he was deemed a primary target by the Black Hand organization.
The most significant group would prove to be the Serbian Narodna Odbrana (National Defence) along with its rather intimidating secret terrorist wing, ‘The Black Hand’. Their intention was to liberate all Serbs from their oppressors to create a Greater Serbia, and in particular to reverse the formal annexation of Bosnia by the Austrians. To this end they had recruited a formidable membership within an interlinked nest of organizations such as ‘Young Bosnia’. The annual summer maneuvers of the Austro-Hungarian army were centered in Bosnia. The army, increasingly frustrated by what it saw as lax government in Austria and Hungary, determined that its administration of Bosnia-Herzegovina should be a model of effectiveness. Franz Ferdinand himself advocated repression and active Germanization. He was also a staunch Catholic: in Bosnia, Catholics were the minority, making up 18 percent of the population, while 42 percent were Orthodox. Many Bosnians looked wistfully to Serbia.