The Serbian campaign of 1914 was a military campaign fought between Austria-Hungary and Serbia at the beginning of World War I. It commenced on July 28, 1914, with Austria-Hungary's declaration of war and subsequent invasion of Serbia, following the assassination of Archduke Franz Ferdinand of Austria in Sarajevo.
The Austro-Hungarian army, initially led by Oskar Potiorek, launched multiple offensives into Serbia, facing fierce resistance from the Serbian army under the command of Marshal Radomir Putnik. The Serbian army, though smaller and less well-equipped, was highly motivated and experienced, having fought in the Balkan Wars of 1912-1913. They also benefited from strong defensive positions and the knowledge of their own terrain.
The first Austrian offensive, launched in August 1914, ended in defeat at the Battle of Cer. A second offensive in September also failed after the Battle of the Drina. A third, more substantial offensive in November managed to capture Belgrade, but the Serbian army counterattacked in December, driving the Austro-Hungarians back across the borders and recapturing Belgrade in what is known as the Battle of Kolubara. The Serbian victory in this battle was significant, effectively repelling the Austro-Hungarian invasion and keeping Serbia free from occupation at the end of 1914. The campaign inflicted heavy casualties on both sides and demonstrated the tenacity of the Serbian army and population in defending their territory. Potiorek was relieved of his command after these failures. The Serbian campaign of 1914 ended as a significant initial Allied victory of the war.