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
Prince Lorenz of Belgium, Archduke of Austria-Este to male primogeniture by declaration of Emperor Franz Joseph I of Austria on 31 October 1914 (following the assassination of Archduke Franz Ferdinand of Austria-Este) and was confirmed by Imperial Austrian letters patent, both of which conferred it (with the traditional coat-of-arms of the House of Austria-Este) upon Lorenz's father, Archduke Robert, on 16 April 1917, and has been confirmed for Lorenz by specific reference in Article IX.1 of the constitution of the Kingdom of Belgium. The "Este" suffix descended by male primogeniture and is borne by Lorenz and his successors as heads of the Austria-Este cadet branch of the