Harry received his medical training at St George’s Hospital, qualifying M.R.C.S., L.R.C.P. in 1891. He gained a commission, at the rank of Surgeon Lieutenant, in the Medical Services on the 27th July 1892. He was then promoted to the rank of Captain on 27th July 1895. From 1897 to 1989, he served in the N W Frontier, India, then in 1902 saw active service in the South African war. He was promoted to Major on 27th July 1904. On the outbreak of war, Harry was stationed in Aldershot, and was posted to be the Commanding Officer to the 1st Field Ambulance, entering the war in France, with the unit, on 18th August 1914. The following day, the 19th September, he was promoted to the rank of Lieutenant Colonel. Harry served as the C.O. of the 1st Field Ambulance up until 31st May 1915, when he handed over command to Lt/Col A W N Bowen R.A.M.C., then returned to England the next day. On 22nd September 1915, Harry served under the rank of temporary Colonel whilst Assistant Director of Medical Services of a Division. In 1916 he became a Companion of the Order of St Michael and St George. On the 3rd January 1918, he was serving as Deputy Director of Medical Services for VI Corps, then became Director of Medical Services at General Headquarters for the Home Services on the 10th August 1918.