World War I service De Roeper joined the
Royal Naval Air Service on 16 April 1915 as a
Temporary Flight Sub-Lieutenant, based at . On 1 July he was granted the Royal Aero Club Aviators Certificate No. 1379 after flying a
Grahame-White biplane at the Grahame-White Flying School at
Hendon Aerodrome, and was confirmed in his rank on 26 October. De Roeper was first assigned to an RNAS Coastal Air Station based at
Redcar,
Yorkshire, flying coastal defence and anti-Zeppelin patrols. He was involved in two separate crashes in 1916, both at Redcar; firstly a forced landing in a
Caudron G.3 on 20 February, and then in a
B.E.2c just after midnight on 3 May, while returning from a patrol, when he struck a searchlight on landing. From there, he was posted to No. 6 Squadron RNAS, where he flew a
Nieuport Scout. On 20 May 1917, he scored his first victory, driving down an
Albatros two-seater out of control north-west of
Bohain. Five days later, on 25 May, he swooped down on a German two-seater, only to be wounded in the jaw by the observer. The wound kept de Roeper out of action until July. As he recuperated, on 4 April he was promoted
Flight Lieutenant and the squadron converted to
Sopwith Camels. De Roeper was awarded the
Air Force Cross while based in Egypt in May 1919.
Inter-war career On 1 August 1919, de Roeper received a full Royal Air Force commission in the rank of
Major (later converted to Squadron Leader), and the following day at
Romford married Jean Julia Key, of
Upminster,
Essex. He then served at the
Central Flying School at
RAF Upavon, before being transferred to the School of Photography at
RAF Farnborough on 15 August 1921, and finally to
No. 1 Flying Training School at
RAF Netheravon on 20 March 1922. On 14 November 1924, de Roeper was proposed by William James Stewart Lockyer to be a
Fellow of the Royal Astronomical Society. On 16 December 1924, he was appointed to the Aeronautical Committee of Guarantee in Germany. This was the successor to the
Military Commission of Control, tasked with the post-war oversight of Germany's industrial production. On 11 March 1925 he was posted to No. 1 RAF Depot at
RAF Uxbridge, and on 16 April, de Roeper left regular Royal Air Force service, being placed on the retired list. De Roeper maintained his interests in aviation, requalifying as a pilot in 1931, being granted Aviators Certificate No. 10158 at
Brooklands Flying School in November, and working in the aircraft industry. By April 1939 he was a
business manager for
Rootes when the
Air Minister Sir Kingsley Wood visited Rootes'
shadow factory at
Speke Aerodrome that was then building the
Bristol Blenheim.
World War II De Roeper rejoined the
Royal Air Force in the rank of Squadron Leader during
World War II, being transferred from the General Duties to the Technical Branch on 24 April 1940. He was promoted to Wing Commander on 1 January 1944, and later to Temporary Group Captain, this being made
war substantive on 24 March 1945. On 3 March 1946, de Roeper returned to the retired list at his own request, retaining the rank of Group Captain. ==References==