Thomas was educated at Newton College, Devon, St Mary's Hospital, London, where he graduated M.R.C.S., L.R.C.P. in 1891. He received a commission in the R.A.M.C. as Surgeon-Lieutenant on 29th July 1893, then became Captain on 29th July 1896. Serving on the North-West Frontier of India from 1897-1898, he was present at the Battle of Shabkadr, and for his service was Mentioned in Despatches on 4th January 1898; received the medal and clasp, and was created a Companion of the Distinguished Service Order [LG 20th May 1898] - “Thomas Herbert John Chapman Goodwin, Surgeon-Capt, Army Medical Staff. In recognition of services in the recent operations on the North-West Frontier of India." (Insignia presented by Major-General Moorsom at Murree on 20th February 1898). Thomas was promoted to Major on 30th January 1905, and became the author of First Aid and Sanitation; Active Service Pocket Book; and Military Hygiene on Active Service (J.R.U.S.I. 1907). Thomas was stationed at Devonport when war was declared. He entered the war at Le Havre, France on 18th August 1914 as Commanding Officer of the 4th Cavalry Field Ambulance, and was present at Mons and the retreat to the Marne - being mentioned in Sir John French’s despatch for his services there. He became Assistant Director of Medical Services for the 2nd Cavalry Division, B.E.F. from 22nd September 1914 - 21 June 1915. He also served with No 14 General Hospital. On 1st March 1915 he was promoted to Lieutenant-Colonel, and became a Companion of the Order of St Michael and St George on 23rd June the same year. From 21st January 1917 to 16th April 1917, he served as Assistant Director of Medical Services, Guards Division, then from April was appointed Assistant Director of Medical Services with Mr Balfour's Mission to America - An unofficial correspondence had taken place between the Director-General of the Army Medical Service and the Surgeon-General of the United States Medical Service, which resulted in Thomas being selected to proceed to the War Department at Washington to liaison between the medical services of the United States and the British Army. He arrived in Washington on 25th April 1917, and put forward a scheme in which the United States may provide assistance to the British with medical and nursing personnel. Three days later, on 28th April, after an interview with the War Secretary, he obtained sanction for the immediate despatch to England six base hospitals, complete in medical and nursing personnel, and one hundred and twelve additional medical officers; he also arranged for further contingents of medical officers and nurses to be despatched at a later date. On 26th December, he was promoted to Colonel and took over from Col M W Russell as Deputy Director-General at the War Office when Col Russell was placed on the retired list on account of age. Thomas was also appointed Honorary Surgeon to the King. He was promoted to Major-General on 18th January 1918, and served as Director-General, Army Medical Services (temporary) from 1st March 1918 to 31 March 1918; then became Director-General, Army Medical Services from 1st June 1918, with the rank of Lieutenant- General. Other awards for his service during the Great War included being Mentioned in Despatched - London Gazette date 4th January 1917; Knight Commander Order of the Bath - London Gazette date 1/1/1919 and awarded the Decoration Ordre de Leopold, Commarifeur by the King of the Belgians - London Gazette date 6th June 1919. On 19 February 1927 he was appointed governor of Queensland, which he continued until the completion of his duties on 7th April 1932 when he returned to England. Thomas died at Oxford, England. He was the eldest son of Surgeon-Major John Goodwin, Army Medical Staff, and of Marion Agnes Power.