Belgrade Offensive and the Niš operation, succeed in clearing Central and Southern Serbia of German forces. These developments put German Army Group E retreating from Greece under intense pressure with the threat of the remaining troops being encircled and cut off from the main German forces. Operation The main forces involved in this undertaking were Bulgarian 2nd Army supported by the Yugoslav 24th and 46th Divisions as well as the 1st through 5th "Kosovo-Metohija" Brigades and the Albanian 3rd and 5th Brigades of the People's Liberation Army of Albania. These forces were assisted by air sorties of the Western Allies and the Soviets against units of Generaloberst Alexander Löhr's Army Group "E" as the latter retreated from Greece. The Axis order of battle against the Bulgarians and Yugoslavs in this operation comprised some 17,000 men including the Kampfgruppe "Langer" with three infantry companies, one artillery battery and one platoon of tanks, Kampfgruppe "Bredow" with six infantry battalions, three artillery battalions and 10 tanks), Kampfgruppe "Skanderbeg" with about 7,000 men of Waffen-SS August Schmidhuber's 21st Mountain Division "Skanderbeg" and about 4,000 German navy personnel making their way to the north from Greece. The Germans were supported by some 10,000 men of the Balli Kombëtar (National Front), the Albanian nationalist, anti-communist and anti-monarchist organisation. The Albanian nationalist forces and the 21st Waffen Mountain Division SS "Skanderbeg" served as the rearguard for the Wehrmacht's retreat, helping the Germans successfully withdraw large forces from Greece and Albania. The SS Skanderbeg was extensively utilised by the Germans, advancing into the mountains and engaging Partisan troops on a daily basis, to cover the flanks of the Wehrmacht. As the offensive against the Germans drove into full swing the SS "Skanderbeg" was issued with orders to increase repression of the Partisan forces and any sympathisers. In keeping with these orders, 131 NLM (Albanian Partisan) prisoners were shot or hanged in Kosovo by members of the division by 23 October. Aftermath Freeing the Kosovo region from the Germans did not bring immediate peace and order. After the Germans had been driven out, Tito ordered the collection of weapons in Kosovo and the arrest of prominent Albanians. The order was not well received and, combined with passions felt about Kosovo, inflamed an insurrection. On 2 December 1944, anti-communist Albanians from the Drenica region attacked the Trepca mining complex and other targets. Numbering at most 2,000 men, these anti-communists managed