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
Archduke Otto of Austria (1865–1906) to repair their relationship with the Saxon royal family, after both Crown Prince Rudolf and Otto's brother Franz Ferdinand had snubbed the Saxons by rejecting Maria's elder sister Mathilde. Otto and Maria had two sons: Their marriage was unhappy, however, since the Archduke was often unfaithful. He had two children by his mistress, Marie Schleinzer: The mountain lodge on the Rax plateau in Lower Austria, is named after him. Archduke Otto of Austria (1865–1906) Otto Franz Joseph Karl Ludwig Maria, Prince Imperial and Archduke of Austria, Prince Royal of Hungary and Bohemia (21 April 1865 – 1 November 1906) was