During the Second World War, Wager worked for the Royal Air Force in the photographic interpretation section. He was commissioned as a pilot officer on 12 August 1940, and promoted to flying officer a year later. In 1942 he braved the notorious Murmansk Run as part of a small reconnaissance team attempting to track down the German battleship Tirpitz. Wager was Mentioned in Despatches for his work. He was promoted to temporary flight lieutenant on 1 September 1942, and the rank was made substantive on 11 February 1943. He resigned his commission on 1 July 1944.