Wanna learn history? Pick up some of the Paradox grand strategy games; Europa Universalis, Victoria, Hearts of Iron, Crusader Kings. A side effect is that you'll pick up a lot of geography by osmosis, which is in my experience, the easiest way to learn that subject - you're looking at maps and borders and terrain features constantly.

Wargaming is in general a good way to pick up information on historical topics. Most developers that are in that niche put a lot of effort into doing the research, and there is typically a lot of information baked into the in-game documentation at your fingertips, not to mention being a springboard for Wikipedia safaris.