The only problem I have with some of the posts on this topic is the assumption that the incomplete nature of the Compiled Service Records is the result of "sanitizing". Occam's Razor posits that the simplest explanation is usually the correct one. The eyewitness accounts of the massive destruction of Confederate records at the end of the war are much more credible than speculation about convoluted conspiracies.
I have no reason to doubt the accounts of several hundred or several thousand blacks accompanying Confederate armies. Based on what I know about the organization, regulations and operations of the Confederate army, they were undoubtedly laborers employed or impressed by the Confederate War Department. I don't doubt for a minute that some blacks served as soldiers in the ranks, but I've read hundreds of letters and dozens of diaries, written by soldiers in each of the Confederate armies, and I've yet to run across a single reference to a black Confederate soldier. I'm not saying there weren't any, I'm just saying that there must not have been nearly as many as some have speculated.