In mid-1944, during the Operation Bagration, Dirlewanger's unit suffered heavy losses during fighting against Red Army regulars. It was then hastily rebuilt and reformed into a "storm brigade" and used in the suppression of the Warsaw Uprising. Historian Martin Windrow wrote that in the summer of 1944 Dirlewanger led his "butchers, rapists and looters into action against the Warsaw Uprising, and quickly committed ... unspeakable crimes." In Warsaw, Dirlewanger participated in the Wola massacre, together with police units rounding up and shooting some 40,000 civilians, most of them in just two days. In the same Wola district, Dirlewanger burned three hospitals with patients inside, while the nurses were "whipped, gang-raped and finally hanged naked, together with the doctors" to the accompaniment of the popular song "In München steht ein Hofbräuhaus". Later, "they drank, raped and murdered their way through the Old Town, slaughtering civilians and fighters alike without distinction of age or sex." In the Old Town – where about 30,000 civilians were killed – several thousand wounded in field hospitals overrun by the Germans were shot and set on fire with flamethrowers. SS-Obergruppenführer Erich von dem Bach-Zelewski, overall commander of the forces pacifying Warsaw – and Dirlewanger's former superior officer in Belarus – described Dirlewanger as having "a typical mercenary nature".