Serbian campaign

The Serbian campaign was a series of military expeditions launched in 1914 and 1915 by the Central Powers against the Kingdom of Serbia during World War I. After an unsuccessful invasion by Austria-Hungary in 1914, the Central Powers launched a successful invasion in 1915 and occupied Serbia. In 1918, after breaking the front in Macedonia, Serbia and its allies liberated Serbia. The first campaign began after Austria-Hungary declared war on Serbia on 28 July 1914. The campaign, dubbed a "punitive expedition" (German: Strafexpedition) by the Austro-Hungarian leadership, was under the command of Austrian General Oskar Potiorek. It ended after three unsuccessful Austro-Hungarian invasion attempts were repelled by the Serbians and their Montenegrin allies. The victory of the Royal Serbian Army at the battle of Cer is considered the first Allied victory in World War I, and the Austro-Hungarian Army's defeat by Serbia has been called one of the great upsets of modern military history. The second campaign was launched, under German command, almost a year later, on 6 October 1915, when Bulgarian, Austro-Hungarian, and German forces, led by Field Marshal August von Mackensen, successfully invaded Serbia from three sides, pre-empting an Allied advance from Salonica to help Serbia. This resulted in the Great Retreat through Montenegro and Albania, the evacuation to Greece, and the establishment of the Macedonian front. The defeat of Serbia gave the Central Powers temporary mastery over the Balkans, opening up a land route from Berlin to Constantinople, allowing the Germans to re-supply the Ottoman Empire for the rest of the war. Mackensen declared an end to the campaign on 24 November 1915. Serbia was then occupied and divided between the Austro-Hungarian Empire and Bulgaria. After the Allies launched the Vardar Offensive in September 1918, which broke through the Macedonian front and defeated the Bulgarians and their...