Bulgaria during World War I 28 June 1914, Gavrilo Princip, a Bosnian-Serb student and member of Young Bosnia, assassinated the heir to the Austro-Hungarian throne, the Archduke Franz Ferdinand of Austria in Sarajevo, Bosnia. This began a period of diplomatic manoeuvring between Austria-Hungary, Germany, Russia, France and Britain called the July Crisis. Wanting to end Serbian interference in Bosnia conclusively, Austria-Hungary delivered the July Ultimatum to Serbia, a series of ten demands that were intentionally meant to be unacceptable in order to precipitate a war with Serbia. When Serbia acceded to only eight of the ten demands levied against it in the ultimatum, Austria-Hungary declared
Archduke Friedrich, Duke of Teschen of the ruling house, Friedrich adopted a military career, and served creditably for many years as commandant of the V. (Pressburg) Corps. Subsequently, commander-in-chief of the Austrian Landwehr (militia) and army inspector, he became, after the murder of the heir to the throne, Archduke Franz Ferdinand, inspector-general of the Austro-Hungarian Army. In World War I, he was —from the dynastic point of view —as grandson of the victor of Aspern, Archduke Charles, and as nephew of the victor of Custoza, Archduke Albert, the predestined head of the armed forces of Austria-Hungary; and on 11 July 1914 Friedrich was appointed supreme