Who is Bennie Lang from The Guns of the South: A Novel of the Civil War and what is their importance?

Bennie Lang served as one of Rhoodie's men. He helped teach the 47th North Carolina regiment how to use the AK-47. Bennir was South African and came from the future. He is adamant about the fact that he does not want the new weapon in the hands of blacks. Trapped in the past, Lang later accepts Lee's offer to help the Confederate States with products and technology.