Serbian Campaign of World War I Serbia, Montenegro, and Greece. When Bulgaria attacked both Serbia and Greece on 16 June 1913, it lost most of its Macedonian region to those countries, and additionally the Southern Dobruja region to Romania and Adrianople (the present-day city of Edirne) to Turkey in the 33-day Second Balkan War, which further destabilized the region. On 28 June 1914, Gavrilo Princip, a Bosnian Serb student and member of a multi-ethnic organisation of national revolutionaries called Young Bosnia, assassinated Archduke Franz Ferdinand of Austria, the heir to the Austro-Hungarian throne, in Sarajevo, Bosnia. The political objective of the assassination was the independence of
Black Hand (Serbia) Balkan Wars. By this point, disagreeing with the Black Hand was dangerous, as political murder was one of their tools. It was also in 1914 that Apis allegedly decided that Archduke Franz Ferdinand, the heir-apparent of Austria, should be assassinated, as he was trying to pacify the Serbians, and if this happened then a revolution would never occur. Towards that end it is claimed that three young Bosnian Serbs were recruited to kill the Archduke. They were definitely trained in bomb throwing and marksmanship by current and former members of the Serbian military. Gavrilo Princip, Nedeljko Čabrinović and Trifko Grabež