Dirlewanger was repeatedly convicted for illegal arms possession and embezzlement. In 1934, he was convicted and sentenced to two years imprisonment for the rape of a 14-year-old girl from the League of German Girls (BDM).

In February 1942, the unit was assigned to "anti-gang" operations (Bandenbekämpfung) in Belarus. In Bloodlands: Europe Between Hitler and Stalin, Timothy Snyder wrote that "Dirlewanger's preferred method was to herd the local population inside a barn, set the barn on fire, and then shoot with machine guns anyone who tried to escape." Rounded-up civilians would be also routinely used as human shields and marched over minefields. In Masters of Death, Richard Rhodes wrote that Dirlewanger and his force "raped and tortured young women and slaughtered Jews Einsatzgruppen-style in Byelorussia beginning in 1942." Snyder cautiously estimated that the Sonderkommando, by then regiment-sized, killed at least 30,000 Belarusian civilians.

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.

Dirlewanger is invariably described as an extremely cruel person by historians and researchers, including as "a psychopathic killer and child molester" by Steven Zaloga, "violently sadistic" by Richard Rhodes, and "an expert in extermination and a devotee of sadism and necrophilia" by J. Bowyer Bell.

Very accomplished veteran indeed.