I'm not an expert on uniforms, so I cannot be 100% sure, but those soldiers look like they are wearing CSA uniforms. The officer is wearign something darker, obviously. It might even be blue. But you have to remember that the entire federal army wore blue in 1860 (before the war). In the early battles, there were quite a few men in blue fighting for the South. It was confusing.
I believe that photo represents a Southern unit, and I believe the officer is CSA -- but I'm not an expert.
They are Union Army uniforms. That is evident by the hats and the overcoats and the presence of brass U.S. badge on the diagonal strap that is centered on the chest and which is visible on several of them. The officer is dressed in the standard U.S. uniform with his rank worn on the shoulder. Confederate officers wore their rank on their collars and their cuffs.
I believe that photo represents a Southern unit, and I believe the officer is CSA -- but I'm not an expert.
Sorry, but you're incorrect.