Around this time, he also began planning guerrilla operations against the Partisans with Gestapo officer Kurt Koppel in the event of Germany's defeat. The number of Partisans in the NDH continued to grow, from a mere 7,000 in 1941, to 25,000 in 1942, and 100,000 in late 1943. On 8 September 1943, the Italians capitulated to the Allies. Countless Italian units surrendered to the Partisans, who disarmed them and thus acquired a significant amount of modern weaponry. Luburić remained sidelined for much of 1944, but his fortunes changed after the Lorković–Vokić plot came to light in August 1944. On 30 August, Luburić personally oversaw the arrests of government ministers Mladen Lorković and Ante Vokić. Lorković, the Minister of Defense, and Vokić, the Minister of Internal Affairs, were accused of conspiring to overthrow Pavelić and install a pro-Allied government. Following their arrests, Luburić was tasked with interrogating Lorković and Vokić, as well as other suspected conspirators. That October, Luburić was promoted to the rank of "Pukovnik" (Colonel). In December 1944, the Croatian Home Guard and the Ustaše Militia were unified to create the Croatian Armed Forces. On 7 December, Luburić forced more than 30 members of the collaborationist Serbian Volunteer Corps off a train passing through Zagreb's main railway station and ordered that they be shot. Destined for Slovenia, they had received Pavelić's approval to pass through Zagreb unmolested, but Luburić showed no regard. In early 1945, Pavelić dispatched Luburić to Sarajevo to undermine the communist fifth column there. Luburić arrived in the city on 15 February. Five days later, Hitler declared Sarajevo a "Festung" (or "fortress"), insisting that it be defended at all costs. Hitler appointed General Heinz Kathner to organize the city's defenses in anticipation of a Partisan attack. On 24 February, Kathner organized a banquet in Luburić's honour. At the banquet, Luburić announced his intention to destroy the communist resistance in Sarajevo. Luburić soon appointed nine Ustaše officers to a special task force for carrying out executions of known and suspected communists. His headquarters was located inside a villa in downtown Sarajevo, which came to be known as the "house of terror" among the city's residents.