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
Emperor of Austria in 1875. As Ferdinand I had no sons, his brother Francis Charles would have become emperor, but was persuaded by his wife to pass over the right of succession to their son, Francis Joseph. He accepted the duty of the Emperor of Austria without having been Crown Prince or "Thronfolger" before. Francis Joseph's only son Rudolf committed suicide in 1889, Francis Joseph's brother Karl Ludwig died in 1896. Karl Ludwig's son Franz Ferdinand became heir presumptive to the throne. He was assassinated in Sarajevo, Bosnia in 1914; due to his morganatic marriage, his son had no rights to the throne.