Missing Objective How can I as a historian use mean, median, mode, and ratios to explore and better understand the Andersonville prison during the Civil War? Background After the breakdown of the prison exchange system in mid 1863, both Union and Confederate forces were forced to hold prisoners for an extended period of time. The Confederacy first held Union prisoners in the capital city of Richmond, VA, but this placed a tremendous strain on the city’s resources. So in early 1864 the Confederacy built a new prison in rural Georgia – Camp Sumter, which quickly became known as Andersonville. By Duration: 90 Minutes.