Tonks entered the
Royal Naval Air Service as a probationary flight
sub-lieutenant with seniority from 13 August 1916. He received
Royal Aero Club Aviator's Certificate No. 4206 after soloing a Maurice Farman biplane at the
Royal Naval Air Service Training Establishment Cranwell on 28 December 1916. Tonks was promoted to
flight lieutenant on 1 January 1918. On 1 April 1918, the Royal Naval Air Service was merged with the Army's Royal Flying Corps to form the Royal Air Force, and No. 4 (Naval) became No. 204 Squadron RAF, On both 10 and 13 August, he drove down another Fokker D.VII, the latter being flown by
Leutnant Dieter Collin, the
Staffelführer of
Jasta 56. On 15 August, he sent down three Fokker D.VIIs out of control east of
Ypres. On 28 September 1918, he destroyed a Fokker D.VII over
Werken, and sent another down out of control. He then turned to low-altitude ground attack missions. until October 1918 when he was rested from combat. Tonks won two Distinguished Flying Crosses in quick succession. The first one, awarded on 2 November 1918, was granted for his valour in aerial combat. His citation read: He received a Bar to the Distinguished Flying Cross in lieu of a second award on 3 December 1918. His citation read:
List of aerial victories ==Post-war career==