In the novel, as in history, Thirteenth Mississippi Lt. Col. Alfred George Washington O’Brien was captured in Fort Sanders. His older sister, Elisa, the wife of radical Unionist Parson William Brownlow, had the privilege of nursing his minor wounds in her Knoxville home.
She tried but was unable to convince him to forsake the Confederacy and “take the oath” to the Union. He chose, instead, to go to Camp Chase, a Union prison just west of Columbus, Ohio’s state capital, and be interned as a POW—until the end of the war, as it happened.
Camp Chase was not the worst Union prison. Point Lookout in Maryland had that distinction. Chase, at least, had wooden huts and tents for shelter (unlike Confederate Camp Lawton in north Georgia, whose exact location was recently discovered), though they leaked when it rained. Deadly disease (including smallpox and typhoid fever) was a constant problem, however, as was the overcrowding of thousands of inmates. Food was not plentiful.
Five men of the Mississippi Brigade (three privates, a sergeant, and a captain) and one private of the Eighteenth Georgia, who were also in the attack on Fort Sanders, died at Camp Chase:
Private William Walker, Co. F, Eighteenth Georgia, who died Oct. 15, ’64
Private J.M. Freeman, Co. K, Seventeenth Miss., who died Mar. 13, ’65
Sergeant Andrew H. Lassiter, Co. C, Seventeenth Miss., died Feb. 24, ’65
Private Howell Smith, Co. A, Eighteenth Miss., no death death listed
Private C.S. West, Co. I, Eighteenth Miss., who died Feb. 1, ’65
Captain Zimmerman R. Mixon, Co. H, Thirteenth Miss., Jan. 29, ’64
They are all buried in the camp cemetery, likely the only Confederate cemetery in Ohio. It has 2,260 graves. O’Brien’s is not among them. He survived and went home at war’s end.
UPDATE: This is also a good site on Camp Chase, especially the photos and maps.