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 Joseph Ferdinand of Austria with more than 70,000 other Viennese. He was interrogated by the Gestapo and sent to Dachau concentration camp, where he was imprisoned for three months. The conditions in the camp ruined his health permanently. Joseph Ferdinand was released and lived an isolated existence thereafter, under continual observation by the Gestapo. He died on 28 August 1942 in Vienna. Archduke Joseph Ferdinand of Austria Archduke Joseph Ferdinand of Austria (24 May 1872 – 28 August 1942) was an Austro-Hungarian Archduke and the titular Grand Duke of Tuscany from 17 January 1908 to 2 May 1921, military commander, from 1916 Generaloberst, and