The son of Herbert Martin and Jessie Maynard, Forster Herbert Martin Maynard was educated in England at St. John's School, Leatherhead and University College, London. He joined the Royal Marines Divisional Engineers on 22 September 1914 and transferred to the Royal Naval Air Service in 1915. Flight Sub-Lieutenant Maynard received Royal Aero Club Aviator's Certificate 1381 on a Short biplane at Royal Naval Air Station, Eastchurch on 1 July 1915. He served as a flight instructor before being posted to Naval 1 at the beginning of 1917. After scoring six victories with the Sopwith Triplane, his days as a fighting pilot ended when he was injured in an air crash while in England. He remained in the Royal Air Force and was granted a permanent
commission to Flight Lieutenant on 1 August 1919. During World War II, Air Vice-Marhsal Maynard was appointed a Companion of the Bath for distinguished service as air officer in command of the Royal Air Force in the Mediterranean.