@Shivertonge: If you read the book, you will see it in Turtledove's style. He likes to make a change to history then write what he thinks will have happen after that. He uses time travel the same way. It is a very good book. You may not see it that way, but you will see the same pattern in Guns of the South as in other books. It is his best and I think most popular book.
It is also smart. Robert E. Lee gets 100,000 AK-47s, but he has these guys act realistically after he gets them.
I'd disagree that it's his best, personally, and I don't know enough to know if it actually is his most popular. I've read a little of it, and while the writing was as good as his other books, the method of the change didn't appeal to me. Time travel always feels cheap to me, and while I understand the every concept of the book relied on it (how else could the Confederacy get AK-47s?) because of it, it just didn't work for me. I've read over thirty of his novels and several collections of his short fiction which I enjoyed much more than I did what I read of Guns of the South. The
Darkness series, where World War 2 is played out in a world where magic works, or
Southern Victory (the previously mentioned Timeline 191) were far more enjoyable, I thought.
Just a difference of opinion. Not saying it's bad, I just don't agree that it's his best.