Dr. Green then went to Paris to continue his medical study, and in 1854–55 returned to Boston to practise. It was on May 19, 1858, that he was commissioned surgeon of the Second Massachusetts Militia Regiment by Governor Banks. On the breaking out of the Civil War he entered the service as assistant surgeon of the First Massachusetts Regiment, and bore the distinction of being the first medical officer of the State to be mustered into the three years' service. He was surgeon of the Twenty-fourth Massachusetts Regiment from September 2, 1861, to November 2, 1864, and had charge of the hospital ship Recruit in General Burnside's expedition to North Carolina, and later of the hospital steamer Cosmopolitan on the coast of South Carolina. He was chief medical officer at Morris Island during the siege of Fort Wagner in the summer of 1863, and was post surgeon at St. Augustine, Fla., in October, 1863, and at Jacksonville in March, 1864. He was with the army at the capture of Bermuda Hundred in May, 1864, and was acting staff surgeon in Richmond for three months following the surrender of that city in April, 1865.
In 1864 he was breveted lieutenant colonel for "gallant and distinguished services in the field."
Dr. Green organized a cemetery on Roanoke Island, one of the first regular burial places for Union soldiers during the war.
For six years after the war he held the position of superintendent of the Boston Dispensary. He was then appointed city physician, and during eleven years the performance of these duties endeared him to thousands by his tender devotion to the poor and the unfortunate.
Dr. Green's interest in city affairs led to his election as mayor in 1882. He served one term only during which he had the satisfaction of turning out of office three police commissioners.
During his life Dr. Green held many positions of trust and was a member of numerous societies. He served as a member of the School Board in 1860–62 and in 1866–72, as trustee of the Boston Public Library in 1868–78, and as acting librarian in 1877. He was a fellow of the Massachusetts Medical Society, delivering the centennial address in 1881 on the History of Medicine in Massachusetts, a useful historical work of reference. Other positions he held were: Member of the Boston Society for Medical Observation, of the Boston Society for Medical Improvement, of the American Philosophical Society of Philadelphia, of the State Board of Health, Lunacy and Charity; president of the Channing Home for Consumptives, overseer of Harvard University; trustee, secretary and general agent of the Peabody Education Fund; a member of the Board of Commissioners to investigate the condition of the records, files, papers and documents in the State Department of Massachusetts, editor of the American Journal of Numismatics, and president of the American Numismatic Society. In 1896 the honorary degree of LL. D. was conferred upon him by the University of Nashville, Tennessee.
In his later life most of his time was spent at the building of the Massachusetts Historical Society, where he was librarian from 1868 until his death. He was a large and portly man, suffered with chronic dyspepsia and his temper was uncertain; several years before his death he had the misfortune to break his thigh by a fall on the street so that the latter part of his life was passed in a wheel-chair.
Dr. Green died in Boston, December 5, 1918, at the age of 88. He was buried in his native town, Groton.
Among his writings are the following publications: "My Campaign in America," a journal kept by Count William de Deux-Ponts, 1780–81, translated from the French MS., with an introduction and notes; "The Story of a Famous Book," an account of Dr. Benjamin Franklin's autobiography; "School Histories and Some Errors in Them"; "Epitaphs from the Old Burying Ground in Groton"; "Early Records of Groton, 1662– 1678"; "History of Medicine in Massachusetts"; "Groton During the Indian Wars"; "Groton During the Witchcraft Times"; "Boundary Lines of Old Groton"; "The Geography of Groton"; prepared for the use of the Applachian Mountain Club; "Groton Historical Series," three volumes; "An Account of the Physicians and Dentists of Groton"; "The Career of Benjamin Franklin," a paper read before the American Philosophical Society, Philadelphia, May 25, 1893, on the 150th anniversary of its foundation, "An Address Before the Old Residents' Historical Association of Lowell," also an account of the library of the Massachusetts Historical Society, and a "List of the Early American Imprints" in the library of that society.
Dr. Green's reputation rests on his record as librarian of the Massachusetts Historical Society, where during his incumbency he saw the library grow from 8,000 volumes and 13,000 pamphlets to 50,000 volumes and
