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 Ferdinand Karl Viktor of Austria-Este had one daughter: Ferdinand, who was a Feldmarschalleutnant (Austrian "two stars" general rank), died at Brno a few months later at the age of 28 from typhus. His widow remarried with Archduke Karl Ferdinand of Austria. Ferdinand is the link in the Jacobite succession between his brother Francis I and his daughter Mary IV and III. Archduke Ferdinand Karl Viktor of Austria-Este Ferdinand Karl Viktor (20 July 1821 – 15 December 1849) was Archduke of Austria-Este and Prince of Modena. Born in Modena, he was the second son of Francis IV of Modena and his niece-consort Maria Beatrice of Savoy.