26 Sept 1918 Special Reserve Commission Lieutenant RAMC.
26 Sept 1919 Captain RAMC.
2 Apr 1923 Permanent Regular Army Commission Captain RAMC.
1923–1924 Served in Iraq.
26 Sept 1930 Major RAMC.
1931 Specialist in medicine.
1924–1936 Served in India.
1 Sept 1939 Acting Lieutenant Colonel RAMC.
Malta 12 Jan 1939 Arrived from England.
Malta 1940 Officer in Charge Medical Division 90 General Hospital Mtarfa. On 1 April 1940, the Governor and Commander-in-Chief Sir Charles Bonham Carter was admitted to General Hospital Mtarfa with basal pneumonia and fell under the care of Major W R D Hamilton. On 5 April, the Governor developed a coronary thrombosis and a joint consultation was held over his medical condition by Major W R D Hamilton and Major John Alexander Davidson. The Lieutenant Governor Sir Edward Jackson took over the administration of Malta while the Governor remained unfit for office. Dr Thomas Forrest Cotton FRCP (1884–1965), consulting physician to the National Heart Hospital and Honorary Consultant Physician to the Queen Alexandra's Military Hospital, was flown over from England. His opinion was favourably and in accord with that of Major Hamilton.
Malta 1941 Officer in Charge Medical Division 90 General Hospital Mtarfa.
Acting OC 90 General Hospital Mtarfa during the illness of the commanding officer Lt Col Henry Bryan Frost Dixon.
June 1941 Awarded the Order of the British Empire.
Malta Mar–Apr 1942 Acting Officer Commanding 90 General Hospital Mtarfa.
Malta 13 July 1942 Two bombs fell in the garden of the house of OC Hospital. Col Hamilton was wounded in the legs and buttocks; his spouse, Florence May, was severely wounded and died shortly after.
Malta 5 Sept 1942 Evacuated by air to England to recover from his wounds. This entailed many months in hospital and multiple operations. Lt Col W V Dunn, who arrived in Malta on 13 November became officer-in-charge Medical Division.
24 Aug 1944 Lieutenant Colonel RAMC.
1945–1946 Served in West Africa as Officer in Charge Medical Division 37 (WA) General Hospital.
1945–1946 Commanding Officer 37 and 68 (WA) General Hospital.
1947–1948 Officer-in-charge Medical Division Military Hospital Cowglen.
4 Sept 1948 Colonel L/RAMC.
1948–1950 Consultant Physician GHQ Middle East Land Force. In Egypt during 1948 to 1950 he had the opportunity of observing a large outbreak of typhoid fever. His thesis on this subject gained him an MD with commendation in 1951.
1 Feb 1951 Brigadier L/RAMC.
1951–1955 Director of Medicine and Consultant Physician to the Army.
16 Feb 1953 Major-General L/RAMC.
17 Oct 1955 Retired. In retirement became a medical advisor to the Army Pensions Office.
5 Oct 1969 Died at the Queen Alexandra Military Hospital London, aged 73 years.