Born in Ballarat, Victoria and a Carpenter by trade, Roy Cooper enlisted on the 28th of October 1915 in the 21st Battalion, 9th Reinforcement, Australian Imperial Force, with the rank of Private, Number 3823, and was listed as returned to Australia on the 7th of July 1919. His Unit embarked from Melbourne, Victoria, on board HMAT A69 'Warilda' on the 8th of February 1916. On the 7th of July 1916 joined 21st Battalion from A.I.F. from the 9th Reinforcements. On the 17th of January 1917 transferred from 24th Battalion to the 21st Battalion and discharged to AIBD. Returned to Australia per 'Chemitz' on the 7th of July 1919. Disembarked on the 5th of September 1919 and Discharged on the 5th of October 1919. Tree No. 1944