Being that this was the area of the field controlled by Louisiana troops... and the evidence of armed and drilled Confederate blacks from Baton Rouge, I question who these men were.. cooks, servants, militia or simply creole Louisianans mis-identified as African Americans. The Gulf region of the Confederacy had a large population of mixed race (normally up to three different catagories) free peoples-- identified as "white" or "mulatto" on the federal census--- strangers to this region might not know what race they were engaging with.
Alabama, once admitted into the Union as a Territory, sent her first two cadets to West Point. One was David Moniac, of South Alabama, a mixed race Creek Indian, who would be the first non-white to graduate West Point. What I mean by mixed race is members of his family were known to be Creek Indian- French/English/Scots - and African.
Ancestry.com and its DNA project is unearthing these facts from peoples of this region with surprising numbers from my research.