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 Ferdinand of Austria employed a staff of sixteen. His authority was reinforced in 1907 when he secured the retirement of the Emperor's confidant Friedrich von Beck-Rzikowsky as Chief of the General Staff. Beck's successor, Franz Conrad von Hötzendorf, was personally selected by Franz Ferdinard. Franz in 1913, as heir-presumptive to the elderly emperor, had been appointed inspector general of all the armed forces of Austria-Hungary ("Generalinspektor der gesamten bewaffneten Macht"), a position superior to that previously held by Archduke Albrecht and including presumed command in wartime. In 1894 Franz Ferdinand met Countess Sophie Chotek, a lady-in-waiting to Archduchess Isabella, wife of Archduke Friedrich,