I know he gives lectures on American history but I've never heard one to qualify them and I've never read is alternative Civil War history books. Basically it's a "what if the south had won" concept if I understand it right.
I have read some of his other non-fiction work however and I know he tends to ignore facts that don't fit his premise. In general I read and listen to him for his political savvy and fundamental ideas about the individuals place in government and governments place in our lives. These are the areas where I really think he shines.