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
Austria–Serbia relations of Serbian revolts during the 1848 Revolutions were not opposed by the Habsburg rulers. Serbian claims were not recognized by Hungary was eventually placated with the Austro-Hungarian Compromise of 1867, further angering Serbian nationalists. One notable flare-up between the two countries was the 1906-1909 economic conflict known as the Pig War which occurred simultaneously with the diplomatic and military crisis over the Austrian annexation of Bosnia. Ultimately, the tensions between the two countries could not withstand the strain of Assassination of Archduke Franz Ferdinand of Austria by Bosnian Serbs in 1914. Following the July Crisis, Austria invaded Serbia to punish