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
Veljko Čubrilović Veljko Čubrilović Veljko Čubrilović (Serbian Cyrillic: Вељко Чубриловић; 6 June 1886 – 3 February 1915) was a Bosnian Serb who was involved in the assassination of Archduke Franz Ferdinand of Austria. He was born in Gradiška, Bosnia and Herzegovina and became a schoolteacher in Priboj Majevički. In 1914, as a member of the Black Hand secret society, he agreed to help Gavrilo Princip, Nedeljko Čabrinović, and Trifko Grabež assassinate Archduke Franz Ferdinand. His brother, Vaso Čubrilović, was also involved in the plot. On Sunday, 28 June 1914, Franz Ferdinand and Sophie von Chotkova were assassinated by Gavrilo Princip. Princip and