Hate to bother you, but I think this would be in your wheelhouse, albeit on the Union side, IIRC. Any suggestions would be greatly apprecaited
Turtledove is good. He is a history professor in addition to an author of alternate history/science fiction works.
A classic alternate history on the victory of the South is Bring the Jubilee, by Ward Moore. The hero, who lives in a world in which the South won the Civil War, travels through time and brings about an alternate history in which the North won at Gettysburg. This might be hard to find. You might have luck using www.bookfinder.com.
If you are interested in the Confederate navy, there is a new book out about the CSS Shenandoah, a Confederate commerce raider that fired the last shot in the Civil War. One of the authors is a descendent of the captain or first officer. The book is Last Flag Down, by Baldwin and Powers. (Powers was co-author of Flags of Our Fathers,)
No bother, but I can see a lot of good recommendations from others right of the bat. “The Killer Angels” is an absolutely fantastic historical fiction, and I cannot recommend it highly enough. I’d start there because if you don’t find that book interested, then you’re not going to find the Civil War interesting. After that, it’s hard to recommend just a “Civil War book” because a lot of them get into specific parts of the war. For a general overview of the war as a whole, McPherson’s “Battle Cry of Freedom” is probably the best single volume history. Shellby Foote did the best trilogy. I’d start there and from that you will probably come across battles or leaders you want to learn more about. From that you can find any number of books that delve into the subject or subjects you choose. Enjoy.
One of the best I’ve read is “Class of 1846” by John Waugh.