Robert Mackay enlisted in Ballarat, Victoria at the age of 19 on the 2nd of July 1917. He had been born in Ballarat, Victoria, was single, and was employed as a Telegraphist. He volunteered and was stationed with the 37th Battalion, Signallers with the Regimental number 47. He was discharged and Returned to Australia on the 27th of March 1919. Tree number 1051.