On 1 February 1960, as part of
National Service, Mayes was
commissioned into
Royal Army Medical Corps as a
lieutenant. He was given the
service number 464204. On 9 March 1960, he transferred to a short service commission in the regular army. He maintained the rank of lieutenant and was given seniority from 14 December 1959. He was promoted to
captain on 14 December 1960. He transferred to a regular commission on 4 March 1964, with seniority in the rank of captain from 14 December 1959. He was promoted to
major on 14 December 1964. During his early career, he served in
Aden, most likely during the
Aden Emergency of 1963 to 1967, in East Africa, in
West Germany with the
British Army of the Rhine and in the United Kingdom. In the same year, he was made a
Consultant in Surgery. From 1984 to 1987, he was
Commanding Officer of the British Military Hospital in
Hannover. From 1987 to 1988, he was Commanding Officer of
Cambridge Military Hospital,
Aldershot Garrison. He was then once more posted to West Germany as a Consultant Surgeon attached to HQ BAOR in 1988. He was Commander Medical, HQ BAOR from 1990 to 1993. He served as Director General Army Medical Services from 1993 to 1996. ==Later life==