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 Peter Ferdinand of Austria Alexander von Krobatin. Peter Ferdinand married Princess Maria Cristina of Bourbon-Two Sicilies, daughter of Prince Alfonso, Count of Caserta and his wife Princess Antonietta of Bourbon-Two Sicilies, on 8 November 1900 in Cannes, France. They had issue: Archduke Peter Ferdinand of Austria Archduke "Peter Ferdinand" Salvator Karl Ludwig Maria Joseph Leopold Anton Rupert Pius Pancraz of Austria, Prince of Hungary and Bohemia, Prince of Tuscany) (12 May 1874, Salzburg, Austria-Hungary – 8 November 1948, St. Gilgen, Salzburg, Austria) was an Austro-Hungarian archduke and an army commander in the Austro-Hungarian Army during World War I. He was also the titular Grand