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.
Macedonian Front The Macedonian Front of World War I, also known as the Salonica Front (after Thessaloniki), was formed as a result of an attempt by the Allied Powers to aid Serbia, in the fall of 1915, against the combined attack of Germany, Austria-Hungary and Bulgaria. The expedition came too late and in insufficient force to prevent the fall of Serbia, and was complicated by the internal political crisis in Greece (the "National Schism"). Eventually, a stable front was established, running from the Albanian Adriatic coast to the Struma River, pitting a multinational Allied force against the Bulgarian Army, which was at various times bolstered with smaller units from the other Central Powers. The Macedonian Front remained quite stable, despite local actions, until the great Allied offensive in September 1918, which resulted in the capitulation of Bulgaria and the liberation of Serbia.