This was a Bulgarian anti-partisan operation designed to limit the growth of Marshal Josip Broz Tito’s Yugoslav partisan movement in north-eastern Serbia (18 March 1944).
General Leytenant Vasil T. Boydev’s 5th Army in Skopje realised that its operations during the winter of 1943/44 had not neutralised the partisans in its area of responsibility, and planned a new operation under the overall command of Polkovnik Stefan Nedev’s 14th Division in the region of Crna Trava, where the ‘Kosovo’ Battalion of the 2nd ‘South Morava’ Partisan Detachment and a number of local units were located.
The Bulgarians deployed seven infantry battalions of the 5th Army, three infantry battalions of General Leytenant Asen D. Nikolov’s I Occupation Corps, two cavalry battalions, two flights of reconnaissance aircraft, 50 trucks, artillery and mortar units, together with the entire police and gendarmerie strength of the Skopje and Sofia regions. The Bulgarian strength was about 8,000 soldiers divided into the Trnava, Niš, Morava and Vlasina Detachments.
Scheduled to last from 15 to 20 March, ‘Radan’ in fact started only on 18 March. After learning of the Bulgarian plans, the partisans started to move through the Rupljanska river valley toward Kačer mountain, and managed to break though at the cost of 30 partisans and four members of a British mission under Major Davis. Boydev ordered the execution of anyone captured in the operational area, and that every village in which resistance was encountered was to be burned to the ground. The Bulgarians admitted to the shooting of more than 200 persons, although German reports indicated that more than 400 had been killed.