Pvt. Mark Marrs served in Capt. Buchanan's Company of McRae's Battalion (later Regiment) Arkansas Infantry. He was not a black man. He was said to be part Cherokee Indian. He can be found in the 1850 and 1860 census of Washington County, Arkansas. I have a note in my files from a descendant several years ago, stating that his full name was Marquis de Lafayette Marrs, but I can't find any verification of that.
There is no record of L. H. Marrs in the Hempstead Rifles; however I only have a transcription of the company's original roster, but no letters or postwar reminiscences from members of the company mention L. H. Marrs or any other black soldier.