After the fall of the Fascist regime and the Armistice of Cassibile, on 13 September 1943 Resega re-established the Milanese section of the PNF, then joining the Italian Social Republic and being appointed federal secretary of the Milan section of the Republican Fascist Party. His son Gianfranco enlisted as an officer in the Republican National Guard. According to Gianni Oliva, Resega represented the "moderate" faction of the Milanese Fascists, trying to curb excesses of the most hardliner elements, led by Francesco Colombo. Nevertheless, his position as head of the Milanese fascists made him a target for the Gruppi di Azione Patriottica, and in the evening of 18 December 1943 he was ambushed and shot dead in front of his home by three GAP members. Eight anti-Fascists were executed in reprisal on the following day at the Arena Civica; the GAP in turn opened fire on Resega's funeral procession on 20 December. When the Black Brigade of Milan was established in 1944, it was named after Resega.[5][6][7][8][9][10]