Roelfzema flew with 139 Squadron. His aircraft was unarmed and relied on its speed to escape from German night fighters and luck to get through the flak. Normally Bomber Command crews were considered to complete a tour after 30 sorties. In the Pathfinder Force crews initially were required to complete 60 sorties but later this was reduced to 45. Roelfzema completed 72 operational sorties, including 25 missions over Berlin, the most heavily defended city in the Reich. For his service the RAF awarded him the Distinguished Flying Cross. While serving in the RAF, Roelfzema flew with pilots and aircrews from other nations that had become occupied by Nazi Germany, whom he saw as comrades in arms. Years later he came to realize that working with Danes, Poles and others gave him a broader sense of the world which he came to appreciate.