While WWII might get the majority of documentaries, movies, and games (video games, tabletop games, and other such), I always preferred learning about WWI. If I weren't doing TGN right now, I'd be finishing up a graduate degree in history, quite possibly studying WWI. It really was the first "modern war" as we know it. Machine guns. Tanks. Aircraft. All were used, either for the very first time, or highly refined and normalized into military tactics during the conflict. CoolMiniOrNot has just released the English version of The Grizzled, a cooperative card game that takes you into the trenches on the Western Front.
In The Grizzled, you and your other squad-mates must head out on missions, playing cards from your hand into the center pile. But if you end up with three of the same symbol out there, the mission is a failure. There's also plenty of danger out there, and you can end up being wounded. Too many wounds and you'll die. The object of the game is to uncover the peace monument before the memorial. If the memorial is uncovered, or if any of the players die, then everyone loses. I had a chance to play the game at the CMON Expo this past year and I really enjoyed it. It seems things are going along so nice and easy, but then it quickly crushes your soul (in a good way).
You can pick up your copy now from the CMON webshop.