[DoodleDawg]

Look at the case of the Richmond Howitzers who fought at 1st Manassas.

I haven't seen any evidence that blacks served as soldiers with the Richmond Howitzers, and Bull Run or anywhere else.

[central_va]

Confederate Ambulance service was basically an all black service.

[Bull Snipe]

There was one. His name was Aleck Kean. He came to the Howitzers with his master John H. Vest. Vest was killed in 1863. Kean remained with the Howitzers, evidently as a cook.
In a 1912 article in the magazine Confederate Veteran, Judge George L Christian states about Kean “I affirm that he was the most faithful and efficient man in the performance of every duty pertaining to his sphere that I have ever known. His whole mind and soul seemed bent on trying to get and prepare something for his mess to eat; and if there was anything to be gotten honestly, Aleck always got the share which was coming to his mess, and he always had that share prepared in the shortest time possible and the most delicious way in which it could have been prepared in camp. The comfort of having such a man as Aleck around us in those trying times can scarcely be described and certainly cannot be exaggerated.”
I would say that it was doubtful if Aleck Kean ever served on gun crew with the Richmond Howitzers.

[DiogenesLamp]

Don't know how credible this is, but i've seen others of a similar sort. Some of it looks like it came from real sources.

A Tribute To Our Black Confederate Heroes

It is entertaining anyways.