The 'Nis Offensive Operation' was a Bulgarian offensive supported by Yugoslav partisan forces and Soviet troops against the German forces of Heeresgruppe 'F' with the object of securing the left flank of the Soviet forces' 3rd Ukrainian Front within the 'Belgrade Strategic Offensive Operation' (8/14 October 1944).
General Leytenant Kiril N. Stanchev’s Bulgarian 2nd Army, operating in concert with forces of the Yugoslav People’s Liberation Army and the Soviet IX Air Corps, was ordered to destroy German troops in the area of Nis in the south-eastern area of Serbia within German-occupied Yugoslavia, and to take the eponymous city. These latter were held by a mix of German army, Waffen-SS and Luftwaffe troops centred on SS-Brigadeführer Otto Kumm’s 7th SS-Freiwilligen Gebirgsdivision 'Prinz Eugen': these 21,500 or so men took the form of 13 infantry battalions supported by 154 pieces of artillery, 164 mortars, 38 tanks and 18 aircraft. The task of this Waffen-SS division was to cover the retreat of the 300,000 German soldiers of Generaloberst Alexander Löhr’s Heeresgruppe 'E' retreating to the north.
The Bulgarian 2nd Army comprised the 4th Division, 6th Division, 9th Division, 12th Division, 2nd Cavalry Division, 1st Sofia Guard Division, 4th Border Brigade and Armoured Brigade.
The National Liberation Army comprised the XIII Corps (22nd Division, 24th Division, 46th Division and 47th Division), the 2nd Proletarian Division, the XIV Corps (45th Division) and a number of partisan detachments.
The Soviet contribution took the form of part of the 57th Army and the IX Air Corps.
The German strength comprised the 7th SS-Freiwilligen Gerbirgsdivision 'Prinz Eugen', Generalmajor Oskar Krämer’s 11th Felddivision (L), Generalleutnant Helmut Friebe’s 22nd Division, 37th Flakregiment and a number of police battalions.
Bulgarian troops entered the fray along the Juzna Morava river, and on 10 October the 'Sofia' Armoured Brigade, with about 150 tanks (mostly ex-German PzKpfw IV battle tanks and the others Czech-built PzKpfw 38(t) and PzKpfw 35(t) vehicles), together with some 40 ex-German Leichter Panzerspähwagen armoured cars and 50 ex-German StuG III assault guns, punched through the defences of the Germans, who then retreated to the west of the Juzna Morava river. On 12 and 13 October Bulgarian troops continued pursuit, and on 14 October parts of Polkovnik Marcho Marchev’s 6th Division 'Bdin', took advantage of the drive to the north by the 'Sofia' Armoured Brigade to seize Nis, driving the German forces farther back.
The German losses totalled some 5,200 men killed and 3,850 men taken prisoner, but the Germans nonetheless managed to hold their position in the Vardar corridor and thus make possible the withdrawal of the remaining German troops.