Flight Lieutenant Colin Russel Leith enlisted in the Royal Australian Air Force in Sydney, New South Wales on 25 May 1941. He first began training courses in New South Wales, Australia. He continued his training in Camp Borden, Canada where he graduated to Pilot on 27 February 1942. On 28 March 1942, Flight Lieutenant Leith was posted to England, where he served with 453 Squadron. After completing further training he served as a Pilot Gunnery Instructor for the 57 Operational Training Unit from December 1943 to June 1944. On 25 July 1944, after completing successful air operations over Lisieux-Orbec, France, Flight Lieutenant Leith's aircraft ran out of fuel and was forced to land in enemy territory. He spent a month fleeing toward the Allies, hiding out in safe houses with the aid of French Resistance personnel and civilians, until his liberation by Canadian troops in August. He reported back to the 453 Squadron in England on 25 August 1944, and continued service in France and England until his return to Australia on 31 August 1945. He was award the Distinguished Flying Cross on 26 January 1945. Flight Lieutenant Leith was discharged on 15 October 1945.