28 July 1914 Start of the Great War.
4 Aug 1914 Britain declares war on Germany.
16 Sept 1914 Granted a Special Reserve Commission Lieutenant RAMC.
30 Sept 1914 Mobilised. Joined No 11 General Hospital, Boulogne in October.
21 Oct 1914–11 Nov 1918 Served with the British Expeditionary Force in France and Flanders.
1 Apr 1915 Promoted Captain Special Reserve RAMC.
1 June 1918 Appointed to a Permanent Regular Army Commission Captain RAMC; commission antedated to 16 March 1918.
1919–1922 Served in India.
13 Sept 1920–16 Apr 1921 Served in Waziristan, North West Frontier British India.
Was granted the rank of Acting Major.
1 May 1921–14 Jan 1922 Granted the rank of Acting Lieutenant Colonel from 1 May 1921.
16 Jan 1923 Transferred from the School of Instruction and appointed Divisional Adjutant 51st (Highland) Division, TA, vice Captain Harold Wordsworth Leach Allott, vacated. Relinquished his rank of Acting Lieutenant Colonel.
Apr 1923 Transferred from Divisional Adjutant, 51st (Highland) Division TA to 49th (West Riding) Division.
Oct 1925 Vacated the appointment of Divisional Adjutant 49th (Okest Riding) Division TA. The post was filled by Captain Hugh Arthur Sandiford MC RAMC.
Malta 16 Apr 1926 Arrived at Malta and was posted to Mtarfa Military Hospital.
16 Sept 1926 Promoted Major RAMC.
Malta 1927 On garrison duty.
Malta 20 Apr 1928 Home leave.
7 Aug 1928 Returned from leave.
Malta 1929 On garrison duty.
Malta 25 May 1930 Home leave.
9 Sept 1930 Returned from leave.
Malta 5 Apr 1931 Returned to England.
1934–1939 Served in India.
1937–1938 Commanding Officer British Military Hospital Sialkot.
1 Mar 1938 Promoted Lieutenant Colonel RAMC.
1938–1939 Commanding Officer British Military Hospital Ambala.
1939 Officer in charge Medical Division Cambridge Military Hospital Aldershot.
1939–1940 Senior Medical Officer Royal Military College Sandhurst.
Jan–Sept 1940 Commanding Officer 14 Casualty Clearing Station.
1 Oct 1940 Acting Colonel.
June–Nov 1940 Served in Palestine.
1940–1941 Commanding Officer 26 General Hospital.
30 Dec 1941 Awarded the Order of the British Empire (OBE). His citation read:
During the active phase of the Greek Campaign, 26 General Hospital was the only British Hospital established. That it was able to expand with rapidity to more than double its normal capacity, and so deal with the large number of casualties which it did, was due to the untiring efforts of the Commanding Officer, Colonel C Popham, who thus played an important part in making possible the evacuation of a large number of wounded who might otherwise have been left as POW.
1940–1942 Served in Egypt. Was wounded in action.
1941–1942 Commanding Officer 32 General Hospital.
1942–1943 Assistant Director Medical Services HQ 71 Sub Area.
1942–1945 Served in Palestine.
1943–1945 Deputy Director Medical Services HQ 21 Area.
1945–1946 Served in North West Europe.
11 Mar 1944 Promoted Colonel L/RAMC.
Aug–Sept 1945 Commanding Officer 113 General Hospital.
1945–1946 Commanding Officer 23 (Scottish) General Hospital.
1946–1947 Commanding Officer Military Hospital Chester.
3 Dec 1947 Retired on to retired pay with reserve liability.
13 Aug 1950 Ceased to remain on the Regular Army Reserve of Officers having exceeded the age limit of liability for recall.
9 Oct 1958 Colonel Cyril Popham of Centre Oak, Blackwater, Camberley, Surrey died on 9 October 1958.