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
Assassination of Archduke Franz Ferdinand wife planned to visit Sarajevo to open the state museum in its new premises there. Duchess Sophie, according to their eldest son, Duke Maximilian, accompanied her husband out of fear for his safety. As Sophie, although of high aristocratic birth, was not from a dynastic family, her union with the Habsburg heir presumptive could only be a morganatic marriage. Emperor Franz Joseph had only consented to their marriage on the condition that their descendants would never ascend the throne. The 14th anniversary of their marriage fell on 28 June. As historian A. J. P. Taylor observes: Franz Ferdinand was an