The son of Walter Blaxland and an electrical engineer from Freemantle, Western Australia, Gregory Hamilton Blaxland enlisted in December 1914. After serving with the 10th Australian Light Horse, he transferred to the Australian Flying Corps in June 1917. On 21 February 1918, Blaxland was posted to 2 Squadron in France, scoring his first two victories in April 1918 as an S.E.5a pilot. On 4 May 1918, believing he was about to score his third victory, he shot down one of Spa86's SPAD XIIIs, killing the French pilot. Following an unsuccessful attempt to cover up the tragedy, Blaxland and his commanding officer were reassigned. While serving with 8 Training Squadron, Blaxland was injured in a crash on 1 July 1918. When he recovered in September 1918, he rejoined 2 Squadron for the duration of the war and was credited with six more victories, all of them Fokker D.VII's.