On 27 June 1915 Strugnell, then a sergeant, was appointed a flying officer and commissioned as a second lieutenant for service in the field. He was posted to No. 1 Squadron RFC, and on 5 February 1916, piloted a Morane-Saulnier L that drove down an Aviatik C.I reconnaissance aircraft for his first victory. Soon after, on 12 February 1916, he was appointed a flight commander with the acting rank of captain. Strugnell served as a flight commander in No. 43 Squadron RFC, from its formation at Stirling on 15 April 1916. On 3 June 1916 he was awarded the Military Cross "for Distinguished Service in the Field". Strugnell spent some time on instruction duty before returning to action flying a Sopwith Pup in No. 54 Squadron RFC as flight commander of "A" Flight. On 19 March 1917, he shared in the setting on fire of a German reconnaissance aircraft. On 14 April and 1 May, he sent another reconnaissance aircraft and an Albatros D.III down out of control. On 11 May 1917, he shared in the destruction of another reconnaissance aircraft, and soon after single-handedly destroyed an Albatros D.III. On 24 July 1917 his award of a Bar to his Military Cross was gazetted. His citation read: On 1 September 1917 Strugnell was appointed a squadron commander with the acting rank of major.
List of aerial victories
Inter-war career
On 1 August 1919 Strugnell was granted a permanent commission in the RAF with the rank of major. He was posted to No. 1 Flying Training School, before being briefly attached the School of Military Administration at Chiseldon from 23 September to 1 November 1921, after which he was assigned to the RAF Depot as a supernumerary officer. On 14 September 1922 he was posted to the RAF Aircraft Depot in Iraq, transferring to the Engine Repair Depot, Egypt, on 18 October 1924, before eventually returning to the UK when posted to the RAF Depot, Uxbridge, on his transfer to the Home Establishment on 9 May 1926. From 1 September 1926 Strugnell served at the headquarters of No. 21 Group at RAF West Drayton. On 1 July 1928 he was promoted to wing commander, and on 1 September was appointed Officer Commanding of No. 9 Squadron, based at RAF Manston, forming part of No. 51 Wing. In August 1930 the Vickers Virginia bombers of No. 51 Wing formed part of the "Blue" forces in the annual RAF Exercises. On 10 January 1931 Strugnell was posted to the Home Aircraft Depot at RAF Henlow for administrative duties. He was promoted to group captain on 3 July 1934, returning to the Middle East to serve as commander of No. 1 Armoured Car Company at RAF Hinaidi, Iraq, until 19 February 1935. He then commanded the Reception Depot at West Drayton from 3 April 1935, and was station commander of RAF Manston from 10 August 1935.