My DS (also 8y) is enjoying the History channel series "America: Story of US", Joy Hakim "History of U.S.", and the flip side graphic novel about the revolutionary war. There are audio books for the the History of US on itunes. I do not know if these would be too much for your son (mine watched the Liberty kids series at 5yr and loved it) but look for yourself
http://www.joyhakim.com/works.htm. These cover american history but there are specific books and chapters that cover just the Revolutionary war. We are also doing a Patriot camp this summer. Ours is run by a local 9/12 project group.
