For the Civil War, do you want to see the battlefields, or do want to see the re-enactments? The internet is your best friend, I would add Arlington as a must see part of the Civil War. Hundreds of small battles and skirmishes fought close to the Mason Dixon line.
As others have said, find a campground, then make daytrips until you see all of the interesting things in an area. Always talk to the park rangers and volunteers, they will give you clues to the best things to see, and where to go next. Many of them have transferred from one park to another.
welcome and enjoy, plus please visit Maine, one of my favorites.