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 Leopold Ludwig of Austria Archduke Leopold Ludwig of Austria Archduke Leopold Ludwig of Austria (German: Leopold Ludwig Maria Franz Julius Estorgius Gerhard Erzherzog von Ósterreich) (b. Milan 6 June 1823 – d. Hórnstein 24 May 1898) was an Austrian general and admiral. He was the eldest son of Archduke Rainer Joseph of Austria (1783–1853) and Princess Elisabeth of Savoy (1800–1856) and a grandson of Emperor Leopold II. Leopold Ludwig was born in 1823 in Milan, where his father served as Viceroy of Lombardy-Venetia from 1818 to 1848. A younger brother, Archduke Rainer Ferdinand (1827–1913), served as Austrian Minister President from 1859 to 1861. Leopold