His next command, as an acting lieutenant-commander, was an unwieldy, ugly coal-burning tug, Gamtoos, whose crew included 17 non-Europeans, the first non-white South African naval personnel to be sent to an active theatre of war. They cleared several Mediterranean ports of sunken and scuttled ships, and at Marseilles Biermann blew a hole in the harbour wall so that he could enter the Vieux Port and begin work. Later he recalled that the most difficult and intense period of his seagoing career occurred when he had to manoeuvre his single-screw ship round an unexploded mine. He was appointed OBE for his distinguished service during the Allied landings in southern France.