Libbie Prison in Richmond housed Union officers captured in the Civil War
Source: National Archives, Virginia, Richmond, Libby Prison (April 1865) and Libby prison, 1865
Major prisons for Union soldiers captured during the Civil War were located in Richmond (Libby Prison, Belle Isle, and Castle Thunder) and Danville.1
Castle Thunder prison was a former tobacco warehouse on the north side of East Cary Street in Richmond
Source: Library of Congress, Castle Thunder - Confederate prison (between 1865 and 1879)
Confederate prisoners were transported out of Virginia to Union prisons
Source: Gardner's Photographic Sketch Book of the War, Group of Confederate Prisoners at Fairfax Courthouse, June 1863 (No.34)
Confederates captured in Virginia were transported to prisons in Maryland, Delaware, and north of the Mason-Dixon Line
Source: National Archives, Camp scene. Guarding Confederate prisoners (Shenandoah Valley, May, 1862)
Confederate prisoners were shipped north after capture by Union forces
Source: National Archives, Camp of Confederate prisoners at Belle Plain, Va., 1864
Source: Gettysburg National Military Park Winter Lecture Series, "Can Those Be Men?" - The Prisoner of War Experience in 1864
in the first two years of the Civil War, it was common to exchange captives rather than keep them in prison indefinitely
Source: Library of Congress, Flag of Truce (1861)
during the Civil War, many Union prisoners were sent to Andersonville, Georgia
Source: Library of Congress, A new batch at Andersonville (by William Waud, 1864-65)
military escorts conducted Civil War prisoners from capture sites on battlefields to prisons behind the front lines
Source: HathiTrust, Harper's Weekly, General Crawford Conducting Rebel Prisoners to His Rear (November 19, 1864, p.748)