My gggrandfather, Nathan Greer, was also captured at Ft. Donelson on Feb. 16, 1862. He was a private and was taken to Ft. Douglas until his release Aug. 1 of that year. My family says he died in Sept. 1862 (in Leatherwood, TN, his home) after the prisoner exchange, that his health was ruined in prison. I've sent off to the National Archives for records. I would like to know the nature of his infirmity or sickness if Camp Douglas kept any records like this. He was in the 48th, Ninth Regiment,Company F., Voorhies. Anyone out there with suggestions?