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 Felix of Austria Archduke Felix of Austria Archduke Felix of Austria (given names: "Felix Friedrich August Maria vom Siege Franz Joseph Peter Karl Anton Robert Otto Pius Michael Benedikt Sebastian Ignatius Marcus d'Aviano"; 31 May 1916 – 6 September 2011) was the last surviving child of the last Austrian Emperor Charles I and a member of the House of Habsburg. He was a younger brother of former Crown Prince Otto of Austria, who predeceased Felix by two months. Archduke Felix was born in the Schönbrunn Palace in Vienna the third son of the then heir presumptive to the throne of Austria-Hungary the Archduke