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
Russian entry into World War I of Austria of Germany and the Austro-Hungarian Empire. The consensus of scholars includes scant mention of Russia, and briefly mentions Russia's defense of Orthodox Serbia, its pan-Slavic roles, its treaty obligations with France, and its concern for protecting it status as a great power. The Archduke Franz Ferdinand of Austro-Hungary was assassinated by Bosnian Serbs on 28 June 1914 to protest Austrian takeover of a largely Slavic province. Vienna was unable to find evidence that Serbia had sponsored the assassination but a month later issued an ultimatum to Serbia, which it knew would be rejected and thus lead to war.