It involved the Central Powers (German, Austro-Hungarian, and Bulgarian units under the command of Prussian Field Marshal Mackensen) and the Kingdom of Serbia.

It was conducted in the southwest corner of Serbia, in the historic site of the medieval battle of Kosovo, where the three Serbian armies, overwhelmed by the combined strength of their enemies, had retreated during the second half of November 1915.

[4] The overwhelming superiority in heavy artillery, as well as the weight of numbers, quickly overwhelmed the Serbian army who started streaming southwards towards Kragujevac and Niš;[5] five days later, the Serbs were caught by surprise when the Bulgarian First and Second Armies invaded Serbia from the east, cutting the rail line that ran north from Salonika and depriving Serbia of reinforcements and artillery ammunition.

[7] The Serbs gradually withdrew, continuing fierce resistance, hoping for the Allies' aid as British and French forces had landed in Salonika.

While determined rearguards held off the forces pressing down on him from the north, the Serbian Chief of the General Staff ordered the rest of the army to pull back toward Kosovo.

[11] Mackensen chose to order a vigorous pursuit in the Ibar Valley, intending to encircle and fight a decisive final battle against the Serbs in the Kosovo area near Priština, known as the "Field of Blackbirds.

On 5 November, the Bulgarian 9th Infantry Division reached and cut the main road running south through Niš and made contact with General Gallwitz's Eleventh German Army.

[14] On 11 November, the Bulgarian First Army, after taking Niš, established contact with the German X Reserve Corps, and then turned to the southwest toward Kosovo in pursuit of the retreating Serbs.

[15] The Germans undertook the most direct pursuit of the Serbians with an expanded X Reserve Corps with the 107th Infantry Division attached to Prussian General Kosch's command.

Buoyed by the recent successful counterattack against the Bulgarians at Leskovac, making a final stand on the Field of Blackbirds also resonated with Serbians from a historical and national standpoint,[b] but a retreat to Prizren and from there across the mountains to the Adriatic coast where the army could rest and refit was the chosen course of action.

[18] However, the ultimate prize that Mackensen and Seeckt sought eluded them as Serbian forces, followed by refugees, had retreated to Prizren and headed toward the Adriatic coast.

[20] On 25 November, the Serbian High Command issued its official order to retreat through the mountains of Montenegro and Albania and join the Allies to continue the war out of the country.

[20] Following this battle and into early 1916, over 400,000 defeated and worn-out Serbian soldiers and civilian refugees, with thousands of Austrian prisoners, retreated toward the Adriatic coast on a terrible trek across Prokletije, the Accursed Mountains, that separate Serbia and Albania, as the snow began to fall.

[22] Although the three attempts to envelop and destroy the Serbian armies had failed, the strategic objective had been obtained as Germany, Austria-Hungary, Bulgaria, and Turkey then controlled a solid swath of territory in the middle of the Eurasian landmass.