In Call of Duty, what are players fighting for?

If you're looking for good video games to use in teaching war, don't use Call Of Duty or the Battlefield games. There is no real story or moral other than "War iz kewl 'cause U git to blow sh** up real gud!"

Instead look at the indie title, "This War Of Mine." It's available through Steam and other sources for the PC. You can probably get a discount from the author since you're a teacher.

Unlike CoD, you don't play a soldier. There are no cool guns or weapons. There is no winning, just cruel, brutal survival. The game is from the point of view of a civilian refugee, who spends his days just trying to survive as a war wages through his country.

Valiant Hearts is another indie game about war. This one centers on some soldiers in the trenches during WW1. It's also not a cheerful game.

After they go through those, THEN you can show them CoD. If you've done your job, my guess is many of them won't be so eager to play it anymore, or will be downright disgusted by its attitude about war, violence and death.

Better yet, talk to them about CoD and military FPS' in general, since they all glorify warfare to an extent, but don't show any bias, only talk of its depiction. Then let them tell you what they think war is like after playing games like that. Then finish up by reading excepts from personal historical accounts of war, I would use first hand accounts of life in WW I trenches, the Rape of Nanking, and Vietnamese POW camps as prime examples. Get them to understand that war is not a game to be idealized and glorified. If I may quote Tolkien's Lord of the Rings, "War will make corpses of us all."