This image from The Atlantic's fabulous Civil War Centennial issue is an interesting juxtaposition. We have a black union soldier sitting in front of a slave auctioneers place of business. No doubt the photogrpaher was well aware of the irony of his image -- one wonders what the soldier thought. Civil war era photographers were not above staging theirr shots -- perhaps understandable as true candid shots were not possible given the tehcnology of the time.
The caption says: A black Union soldier sits, posted in front of a slave auction house on Whitehall Street in Atlanta, Georgia, in 1864. The sign reads "Auction & Negro Sales".