The Battle of Kolubara, was fought between Austria-Hungary and Serbia in November and December 1914, during which campaign of World War I was fought from late July 1914, when Austria-Hungary invaded the Kingdom of Serbia at the outset of World War I, until the war's conclusion in November 1918?
Battle of Kolubara The Battle of Kolubara (Serbian: Колубарска битка, "Kolubarska bitka" , German: "Schlacht an der Kolubara" ) was fought between Austria-Hungary and Serbia in November and December 1914, during the Serbian Campaign of World War I. It commenced on 16 November, when the Austro-Hungarians under the command of Oskar Potiorek reached the Kolubara River during their third invasion of Serbia that year, having captured the strategic town of Valjevo and forced the Serbian Army to undertake a series of retreats. The Serbs withdrew from Belgrade on 29–30 November, and the city soon fell under Austro-Hungarian control. On 2 December, the Serbian Army launched a surprise counter-attack all along the front. Valjevo and Užice were retaken by the Serbs on 8 December and the Austro-Hungarians retreated to Belgrade, which 5th Army commander Liborius Ritter von Frank deemed to be untenable. The Austro-Hungarians abandoned the city between 14 and 15 December and retreated back into Austria-Hungary, allowing the Serbs to retake their capital the following day.
Bosnian crisis The Bosnian crisis of 1908–09, also known as the Annexation crisis or the First Balkan Crisis, erupted when on 8 October 1908, Austria-Hungary announced the annexation of Bosnia and Herzegovina, territories formally within the sovereignty of the Ottoman Empire. This unilateral action—timed to coincide with Bulgaria's declaration of independence (5 October) from the Ottoman Empire—sparked protestations from all the Great Powers and Austria-Hungary's Balkan neighbours, Serbia and Montenegro. In April 1909 the Treaty of Berlin was amended to reflect the "fait accompli" and bring the crisis to an end. The crisis permanently damaged relations between Austria-Hungary on one hand and Serbia, Italy and the Russian Empire on the other. The Italian historian Luigi Albertini regarded it as laying the grounds for World War I. Although the crisis ended with what appeared to be a total Austro-Hungarian diplomatic victory, Russia became determined not to back down again and hastened its military build-up. Austrian–Serbian relations became permanently stressed.