After serving with the 4th Irish Rifles, Giles Noble Blennerhasset was seconded to the Royal Flying Corps on 24 March 1916. Posted to 18 Squadron, he scored eight victories as an F.E.2b observer. On 19 July 1917, he was posted to Home Establishment and, after becoming a pilot, served with several Home Defence squadrons. Toward the end of 1919, Blennerhasset was posted to India and served with 48 Squadron until October 1920. He left the Royal Air Force on 22 January 1921.
Military Cross (MC)
2nd Lt. Giles Noble Blennerhassett, R. Ir. Fus., Spec. Res., and R.F.C.
For conspicuous gallantry and devotion to duty. He has shown great skill and courage when, acting as escort in attacking hostile formations. On one occasion he attacked two hostile machines, driving down both out of control. Later, he forced three other machines down.