Glad to help. You are right, based on his description, I don't think it was a regular stars and stripes. With all of that wording on it, if it was a regular stars and stripes, it would have been too crowded to fit on the canton and would have been on the stripes as is seen in surviving examples. Something the Confederates would have seen often in the long war, so not particularly 'beautiful'. This almost certainly was a large blue flag with, I imagine, the 13th U. S. Colored Inft. on the top of the eagle and the rest on the bottom.