It was an enjoyable read for me back as a kid even though I knew little history. It's pretty strong on the wish fulfillment end of things. E.g. big bad ass Americans go back in time and are better than everyone else. That sort of thing can still be fun, though, if you need to relax.

I didn't even remember where the 30 years war was, and here I am recommending the series. The history is provided, you're not expected to know it.