Battle of Cer On 28 June 1914, Bosnian Serb student Gavrilo Princip assassinated Archduke Franz Ferdinand of Austria in Sarajevo. The assassination precipitated the July Crisis, which led Austria-Hungary to issue an ultimatum to Serbia on 23 July on suspicion that the assassination had been planned in Belgrade. The Austro-Hungarian government made the ultimatum intentionally unacceptable to Serbia, and it was indeed rejected. The Austro-Hungarians declared war on Serbia on 28 July and that same day the Serbs destroyed all bridges on the Sava and Danube rivers in order to prevent the Austro-Hungarians from using them during any future invasion. Belgrade was shelled
Archduke Ferdinand Karl of Austria Archduke Ferdinand Karl of Austria Archduke Ferdinand Karl of Austria, later known as Ferdinand Burg (Ferdinand Carl Ludwig Joseph Johann Maria; Vienna, 27 December 1868 – Munich, 12 March 1915) He was the third son of Archduke Charles Louis of Austria and Princess Maria Annunciata of Bourbon-Two Sicilies. Archduke Franz Ferdinand, whose assassination at Sarajevo on 28 June 1914 launched World War I, was his elder brother. He was a major-general in the Austrian Army. Like his brother, in 1909 he concluded an unequal marriage with Bertha Czuber (1879–1979), daughter of Emanuel Czuber. Unlike his brother, he did so without