When looking up information, I always start with Wikipedia. Some people criticize that for some reason. I don’t understand why. First, they provide a great overview to get you started, and they have everything in one convenient location. You add to that the fact that not only does it list the various connections, (what battles the unit or general was in, etc.) but they have links! These links become enormously helpful.
But here’s what’s specifically great about Wikipedia: They list their sources, with links, at the bottom of the page. That’s right, if I want to learn more about what I’m reading, I can click on those links and find out more, or learn where to buy a book I need, etc.
I also have a small library of Civil War books. The most useful one, of course, is Shelby Foote’s The Civil War. Nothing is more complete, and easy to navigate. As I was making each book, I read through the years of which I was writing in Foote’s book, occasionally picking up something to use I hadn’t gotten out of Wikipedia. I also had Ken Burn’s documentary running almost on a continuous loop on the specific year of which I was writing. This provided inspiration and, again, small ideas I hadn’t considered before.
And, as I said, I have a few other books that I went through to find a bit more to put in. For instance, I knew there was something interesting Forrest had done in ’64 that I wasn’t seeing in my regular sources, so I picked up his biography again and found it, placing it in as one of his special rules.
A more specific example of something that came out of Foote’s book was Longstreet’s special ability to create a flank attack. I knew he had played an important role in the Battle of the Wilderness, coming in at just the right time to hit the Federals and taking them by surprise; but what I had forgotten was that he split up a brigade, creating a separate one under a temporarily promoted officer. This way the Federals thought they knew where every Confederate brigade was, and was therefore surprised when a new one appeared on their flank. As such, his rule allows him to break up a brigade and have a new one appear within a certain distance and attack.