 Between 1939 and 1940, Hughes was a member of the AMF 4th Division, 6th Field Ambulance.He had enlisted at the outbreak of the Second World War but was ordered to return to his studies in 1940 so as to complete his medical training.Between 1950 and 1951, he served as a lieutenant-colonel and senior surgeon at Kure Hospital, Japan, as a member of the British Commonwealth Occupation Forces in the course of the Korean War.