18 Squadron RFC to fly in F.E.2b two-seaters, he gained his first aerial victory on 4 February 1917, driving down out of control an Albatros D.II fighter.
His citation read: He subsequently qualified as a pilot, being promoted to lieutenant on 2 December 1917,[6] and appointed a flying officer the next day.
[10] On 24 October 1919 Blennerhassett was granted short service commission in the RAF with the rank of flying officer.
[12] As a lay representative of the Church of Ireland he donated the Bishop's Throne to St John the Baptist Cathedral, Sligo, in memory of his father.
He married twice; first to Kathleen Maud Curry of Newbridge, County Kildare at Aldershot, Hampshire on 8 January 1918, and secondly to Dorothy Margaret Pinnock in 1932.