Stuart was educated at Elgin Academy and at Aberdeen University, qualifying M.B. in 1884. He gained a commission in the R.A.M.C. at the rank of Captain on 5th February 1887, and then went to N.W. Frontier, India from 1897 to 1898. On 5th February 1899 he gained promotion to Major, and was promoted again to Lieutenant Colonel on 29th July 1911. Stuart was stationed in Salisbury when war was declared. He entered the war in France on 9th August 1914 and served as Medical Officer for embarkation duties at H.Q. No 2 Base, until 10th October, when he became the Officer Commanding No 1 General Hospital. He gained further promotion to Colonel on 1st March 1915, then on the 15th April, reported his arrival to take up the appointment of Assistant Director of Medical Services with the 1st Division. He remained in this post until November 1916, when he became Deputy Director of Medical Services to the 3rd Army Corps, and remained in this post until April 1918 when he returned to the UK and served at H.Q., London. He retired from the Army in 1920, at the rank of Major General. During his army career he earnt the Most Honourable Order of the Bath, C.B. (Military); The Most Distinguished Order of St Michael and St George, C.M.G., and had been appointed Honorary Physician to the King.