My 6 year old LIVES for history stuff. He went to Antietam and the Battle of Cedar Creek reinactments this year! So fun! I love it too, so I love that he is so excited for it.
He even asked for a picture of a soldier leader for Christmas :). I'm going to print O. of him in the clothes he put on and frame it for his room.
Sorry about not being able to give more advice on it. Not sure about toys. Can you do battle field tours with him? You're probably not far from Gettysburg and only a few hours from many other ones.
ETA - right on Victoria!! DC is a breeding ground for amazing history!! LOVE IT!! And there are tons of hotels close for a great price.
Denise - if you come to DC, do the Dullus Air and Space Museum...you beat the crowd in DC and it's got a lot more stuff :).