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
Trialism in Austria-Hungary and Serbs. The curiosity is that no act of Sabor dethroned king Karl I, nor did it acknowledge the entering in a state union with Serbia, which is today mentioned in the preamble of the Constitution of Croatia. Trialism in Austria-Hungary In the history of the Austria-Hungary trialism was the political movement that aimed to reorganize the bipartite Empire into a tripartite one, creating a Croatian state equal in status to Austria and Hungary. Franz Ferdinand promoted trialism before his assassination in 1914 to prevent the Empire from being ripped apart by Slavic dissent. The Empire would be restructured three