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 Franz Ferdinand of Austria Duke of Teschen. Franz began to visit Archduke Friedrich's villa in Pressburg (now Bratislava), and in turn Sophie wrote to Franz Ferdinand during his convalescence from tuberculosis on the island of Lošinj in the Adriatic. They kept their relationship a secret, until it was discovered by Isabella herself. To be eligible to marry a member of the imperial House of Habsburg, one had to be a member of one of the reigning or formerly reigning dynasties of Europe. The Choteks were not one of these families, although they did include among their ancestors, in the female line, princes of Baden,