[1] During the American Civil War, he was the Confederate States Army's assistant surgeon with the 10th Georgia Infantry Regiment, and went on to become dean of Savannah Medical College and an alderman of the city.
[4] He then graduated as a Doctor of Medicine from Savannah Medical College in March 1861 and, four years later, from Rotunda Hospital in Dublin, Ireland.
[5] During the American Civil War, he was assistant surgeon in the Confederate States Army, and served in field hospitals in both Savannah and Harrisburg, Pennsylvania.
In July 1876, Duncan was the first doctor to treat J. W. Schull, the first victim and believed source of the yellow fever epidemic to hit Savannah and the United States that summer.
[7] Duncan was an alderman of Savannah for twelve years, and was also a member of the city's Board of Sanitary Commissioners.