I just finished reading your timeline, and I have some questions.
1. The POD: First, why does Jackson include lowering tariffs as part of his platform? For the election of 1828, Jackson, although in favor of lowering tariffs, remained vague on that issue, like all others. He would just give statements that made it seem he could go either way, that way he would earn more votes; he did that for every issue. Second, Jackson and Calhoun didn't like each other at all; they were never friends. Calhoun didn't like Jackson, and only agreed to be his VP because he assumed that Jackson was so old, he'd either die or serve one term, thus propelling Calhoun into the White House; he did it purely for political reasons. Jackson didn't like Calhoun because he knew he couldn't trust him, and Jackson would die to preserve the union, and Calhoun had already begun to associate himself with the would be secessionists. This mutual hatred was expanded ten fold after the Petticoat Affair, which still happens in your timeline. I don't think Jackson would keep Calhoun as his VP for a second term under any circumstances.
2. Robert E. Lee: I have several questions with Lee. First, why does he decide to betray his state? Lee was willing to die for Virginia, and what would make him decide to fight against it in TTL? And Lee was strictly apolitical in OTL. Why would this change as well in TTL? And if only the one in a million chance he did decide to run for President, he would not be a Republican under ANY circumstances.
3. Ulysses S. Grant: I think you need to fill Grant's life in A LOT. After he signed up for the military once again and trained troops for a few months, he was promoted to colonel in OTL. It would seem that in TTL, he'd either be a colonel or something close to it. But it seems that once the war starts in TTL, he is immediately in command of an enormous field army. How did that happen?
4. War of Secession: Why? The way the war starts in TTL, its just so sudden and seemingly unprovoked. Our war started after over a decade of increasing tension and insults to both sides. Maybe, during the crisis after Houston's death, South Carolina secedes in a panic, but it seems like having the whole deep south secede and the coastal states, it just seems kind of ASB. Secession in OTL was an organized affair, not a spur of the moment event.
5. John C. Fremont: Why is he so moderate in TTL? John C. Fremont in OTL was just nuts. And if somehow he becomes President, there might as well not even be a south. Fremont would make reconstruction so bad, the south would be crushed into dust. The Democrats probably wouldn't be able to elect someone for decades and decades. Why would he be any less radical in TTL?
6. Nathan Bedford Forrest: Why is Forrest in the war? Tennessee was on the union's side, why would he join the Confederate cause? And its the same thing with him as with Grant. In the beginning of the war, you have him commanding one of the main Confederate armies. Forrest entered into service as a private, and it took 4 years for him to be a Lieutenant General. He was a military mastermind, but it would take him quite a while to reach the top.
7. Thomas Jackson: I'm just curious why it took so long for him to make an appearance, especially after Grant and Forrest came in so early.
8. Don Carlos Buell: How does he become a good general? He was a great organizer, and planner, but when it came to battle he was just terrible. Hell, he barely beat Braxton Bragg in OTL, one of the worst generals of the war. How can he compete with Forrest and Longstreet?
9. George B. McClellan: Same as Buell, how does he compete with Longstreet and such.
10. James Longstreet: As a lot of people have already mentioned, the whole town burning thing.
11. I have a feeling that your going to explain a lot of the differences with the people as just butterflies. But if they're historical people, then they have the same parents, and odds are they'll pretty much the same childhoods and experiences as before; their personalities and such should be if not similar the same; especially since its only 30 years or so since the POD, so things are really diluted enough for people to be polar opposites or anything like that. Technically you could put it up to butterflies, but I don't think that's really explaining anything.
On a lighter note, I think you've done a really good job on the 1880s and 1890s, and I absolutely LOVE what you've done with Europe. I'm definitely subscribing to the timeline
