This was a German and Croat operation to prevent the partisan forces of Marshal Josip Broz Tito from entering northern Macedonia from the south of German-occupied Yugoslavia (15 July/2 August 1944).
Aware of the imminent German withdrawal from Greece and the Soviet advance through the northern Balkans, the partisans rushed the first of an estimated 13 divisions in the direction of the strategic area to the north of Skopje.
Supervised by SS-Obergruppenführer und General der Waffen-SS Arthur Phleps’s V SS Gebirgskorps, the operation was undertaken largely by German forces, in the form of SS-Brigadeführer und Generalmajor der Waffen-SS Otto Kumm’s 7th SS Freiwilligen Gebirgsdivision 'Prinz Eugen' and SS-Brigadeführer und Generalmajor der Waffen-SS Desiderius Hampel’s 13th SS Gebirgsdivision 'Handschar' (kroatisch Nr. 1), supported by Croat units and a number of Ustaše and Četnik elements, and was fought simultaneously with ‘Draufgänger’ (iii) in Montenegro.
The German and Croat forces were organised in three groups, namely the Kampfgruppe 'Süd' (two battalions of the 7th SS Freiwilligen Gebirgsdivision and one of the 13th SS Gebirgsdivision) to attack attack from Sokolac toward Vlasenica; the Kampfgruppe 'Ost' (2/28th SS Freiwilligen Gebirgsjägerregiment and 3/28th SS Freiwilligen Gebirgsjägerregiment of the 13th SS Gebirgsdivision) to operate in the direction of Zvornik and Sekovici; and the Kampfgruppe 'Nord' (1/27th SS Freiwilligen Gebirgsjägerregiment and 3/27th SS Freiwilligen Gebirgsjägerregiment of the 13th SS Gebirgsdivision) to advance from the Spreča river valley towards Prnjavor and Zivinice. Each of these Kampfgruppen was supplemented by local Croat, Ustaše and Četnik elements, which helped largely through the provision of local information.
The operation began on 15 July as the Kampfgruppe 'Nord' and Kampfgruppe 'Süd' advanced with three and one battalions respectively, and as soon as it learned of the German effort, the staff of the Yugoslav III Corps attempted to organise a co-ordinated response of its formations and units with those of the Yugoslav XII Corps to halt the German advances and prevent the penetration of German forces into the Drinjača river valley.
On 18 July the Germans extended the scope of their operation into the area of Kladanj, Vlasenica and Sokolac against the formations and units of the Yugoslav III Corps, the German forces being reinforced by 2,000 to 3,000 Četniks of the 'Majevica' Corps and about 1,500 local volunteers from the Spreča river valley.
From 20 to 22 July, the Germans made their primary effort against Bačkovcu, and achieved some success through clever use of local physical conditions, especially woodland, to ambush the Yugoslav forces, but the arrival of the Yugoslav 15th Moslem Brigade then helped to check the German progress. The Germans occupied Bačkovcu with a force of between 600 and 1,000 men, but these were attacked several times by the 16th Moslem Brigade, which had a strength of only 250 to 300 men, on 21 and 22 July, and the 13th SS Gebirgsdivision lost an estimated 200 men killed and wounded.
‘Röslein’ cost the Germans almost 1,000 casualties, but even so was unable to prevent a strong partisan force from seizing a stretch of the main road to the north of Skopje on 2 August. A hastily formed task force, with a reconnaissance battalion as its nucleus, managed to drive away the partisans in heavy fighting.