This represents one-half of an 8x10 stereograph glass plate negative. It's labeled as "Chattanooga, Tenn. Confederate prisoners at railroad depot" . However, as we've seen in other photos, many people knowledgeable of Civil War uniforms do not believe these are Confederate prisoners. Instead, the most popular theory is that they are Union soldiers preparing for transport.
In a few short months, enormous resources were poured into the city as the base for Sherman's Atlanta campaign. The year following Chattanooga’s fall to Union forces is well documented by many photographers, this one thought to be taken by George N. Barnard.