Samuel was educated at Cheltenham, then received his medical training at St Thomas’s Hospital and at King’s College, qualifying M.R.C.S., L.R.C.P. in 1888. As soon as he qualified he joined medical services. On 1st February 1890 he saw promotion to the rank of Captain, then served throughout the Chitral Campaign in 1895 in medical charge of the 1st Bn Gordon Highlanders and No 8 Mountain Battery Royal Artillery, gaining a medal and Clasp. In 1989 he gained a Diplomas in Public Health (D.P.H.) From 1899 to 1902 he saw active service in South Africa, receiving special promotion to the rank of Major, on 29th November 1900, for his service there. He was also Mentioned in Despatched twice, and gained the Queens Medal with 6 clasps and the King’s Medal with 2 clasps. On 16th November 1901 he was attached Surgeon Major to the Scots Guards, a post he held until 17th April 1909. Outside of his military duties during this time he was P.M.O of the National Rifle Association from 1908 to 1914. On 9th March 1912 he gained promotion to Lieutenant Colonel.
Samuel entered the war on 27th September 1914, as D.A.D.M.S. of the 7th Division. On 1st November he took over the role of A.D.M.S., 1st Division when Lt/Col Gerald Cree became unwell. He appears to have remained in this position until the end of 1914, however by 13th March 1915 he was medically in charge of No 7 General Hospital, Malassise, whereby, during the Battle of Neuve Chappelle, he was instructed by the D.G.M.S. to proceed to Merville to assist with controlling evacuation via motor ambulance convoys. He arrived after the main pressure had ended, so returned to Malassise on the evening of the 15th. During this time he had received promotion to the rank of Colonel on 1st March 1915. He became a Companion of the Order of Bath (military) in 1915, and was awarded the Order of Leopold (Officer) 1916, as well as receiving the French Croix de Guerre.
During the Battle of the Somme 1916 he was serving under the post of Assistant Director of Medical Services, 29th Division. On 18th January 1917 he had became Deputy Director of Medical Services, II Corps, then on 8th April 1918 he took up the role of Director of Medical Services, 2nd Army (succeeding Surg-General R Porter when he retired), a position he held to the end of the war and into the Army of the Rhine.
Samuel was then appointed Commandant of the R.A.M.C. College in Grosvenor Road, and soon after was given a post in the Aldershot Command, which he held until he retired from service in 1923. After he retired he was made house governor and medical superintendent of Osborne Convalescent Home for Officers, which he held from 1924 to 1931. In 1924 he was also in medical charge of the British Empire Exhibition at Wembly.
In 1925 he gained promotion to Knight Commander of the Order of Bath, then in 1931 a Knight Commander Royal Victoria Order; and was appointed honorary surgeon to the King. He died at Wilton Lodge, Cheltenham. Samuel was the son of Colonel S. Guise-Moores, late The Devon Regiment; and the husband of Kate Louise, daughter of Capt Wood, R.E. - they had one son.