Bruce qualified M.R.C.S. in 1879 and L.R.C.P. & L.M. in 1881 at St George’s Hospital. He took up a commission with the Medical Service on 29th July 1882 at the rank of Surgeon Captain. He gained promotion to the rank of Major on 29th July 1884. From 1897 - 1898 he served with the N.W. Frontier, India. He then served in South Africa from 1899 - 1901, during which time he was granted a local rank of Colonel whilst P.M.O of Division, Field Force, South Africa from 23 July 1900. On 29 July 1902 he gained promotion to the rank of Lieutenant Colonel, and from 1902 - 1907 was secretary to the Advisory and Nursing Boards. During this time, in 1906, he was granted a Member of the Royal Victoria Order. He gained further promotion to the rank of Colonel on 4th May 1912, and from 15th August 1912 to 4th August 1914 was the Commandant and Director of Studies at the R.A.M. College. Bruce entered the war in France on 14th October 1914, where he proceeded to Boulogne to establish a Base. On 19th October, he was transferred to the Rouen Base, where he assumed the duties of Assistant Director of Medical Services (A.D.M.S.). On 6th April 1915 he was posted to become the Deputy Director Medical Services (D.D.M.S.) for III Corps. He became a Companion of the Order of St Michael & St George on 11th January 1916. From 1st November 1916 he served as the Director of Medical Services (D.M.S.), 5th Army, under the temporary rank of Major General. On 2nd April 1918, the 5th Army was re-formed as the 4th Army. Bruce continued to carry on the duties of D.M.S. until 8th April when the role was taken over by Major-General O’Keeffe.