Mahaddie's final assignment during the war came 24 July 1944 when he was made Officer Commanding at RAF Warboys, the airfield that was the home of the Pathfinder Force Training Unit. He took over the command from Group Captain J. H. Searby, a pilot whom Mahaddie had earlier recruited to the Pathfinder Force, famous for being the Master Bomber on the Peenemünde raid. The unit trained aircrew on the Avro Lancaster and the De Haviland Mosquito. Mahaddie was again Mentioned in Despatches on 1 January 1945. The last wartime sortie he flew was in leading a flight of 60 Lancasters to repatriate RAF PoWs held at Lübeck.