Excellent book! Sequel, ok but not as good as I recall. Are there more than two in his Cival War series? Never read his WWII series of alternate realities, though.
There was a sequel? I thought the other Civil War books he wrote were along a different path, not necessarily on the same timeline. But they aren't bad at all.
I thought the WWII stuff was better, somewhat because it's a little easier to miss anachronistic stuff when the book is more recently based, but also because it's a tad more sci-fi and later in his writing. I think he has improved as he has written more.
He also wrote one about Elizabethan England being subjected to Spanish rule, with Shakespeare as its main character. Probably his best--it's called "Ruled Britannia."