Instead of invading Maryland and Pennsylvania, wouldn't it have been a good idea to follow up victories by trying to take Fairfax and Alexandria (now Arlington) Counties? Why not try to control the Virginia side of the bridges to DC? That would threaten an attack on the capital and make it more difficult for the Union Army in Virginia to be supplied. I realize that area was heavily defended and had many forts, and I assume that was the reason. However, I wonder why there wasn't more attempts to move toward Washington.