And then a battlefield was rediscovered at the Harz mountains.
If you're looking for any military stuff from any nation: The moment they had a war against Germany you find their stuff there. Just dig a bit.
Also the "hostile Germanic lands" weren't neccessarily that hostile. Mind that Germany back then was tribal and while some tribes indeed fought the Romans a lot didn't and even had trade relations with them. As long as some asshat didn't bring a couple of legions or wanted a lot of money from them Germans were like "I don't care, more beer please!".
As opposed to the continual warfare with the Parthians. If you don't mind the towels lying around your limes forts Germans aren't that bad...