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–Germany relations in this unified Germany. Austria-Hungary then turned its imperial ambitions to the Balkan Peninsula; whereas the German Empire focused on building armaments in a race against the United Kingdom (Britain and Ireland). Nevertheless, both the German Empire and Austria-Hungary forged a military alliance with the Kingdom of Italy, forming the Triple Alliance (1882). In the 1910s, Austria-Hungary's ambition of turning Serbia into its protectorate facilitated the Assassination of Archduke Franz Ferdinand (1914), heir to Austria-Hungary's throne. When Austria-Hungary stirred up excuses for a war (First World War) against Serbia, Germany, claiming the Alliance's terms of passive military defence instead of