Battle of Kolubara their respective commands, and the 5th and 6th armies were merged into a single 5th Army of 95,000 men. 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
Archduke Franz Karl of Austria Archduke Franz Karl of Austria Archduke Franz Karl Joseph of Austria (17 December 1802 – 8 March 1878) was a member of the House of Habsburg. He was the father of two emperors: Franz Joseph I of Austria and Maximilian I of Mexico. Through his third son Karl Ludwig, he was the grandfather of Archduke Franz Ferdinand of Austria – whose assassination sparked the hostilities that led to the outbreak of World War I – and the great-grandfather of the last Habsburg emperor Karl I. Franz Karl was born in Vienna, the third son of Emperor Francis II (I) by