Oh, I know! How about a war with a lot of conscripts such as any of the World Wars or wars involving Sweden or Norway? Here's how they match up:
1) in a highschool setting you have characters who are still coming to grips with their own emotions and learning how to do thingsBeing in the middle of a war is pretty emotional, and even with boot camp you're going to have to do a lot of thinking on your feet.
2) Highschool is a highly social setting about who you know, who you are friend with, who are your enemiesJudging by how catty the various divisions of the army are with each other (And by the army, I mean
every army) and the fact that these are the people who are meant to stop you from being shot, you definitely need to know who has your back or who doesn't care about you.
3) Highschool has clubs and activities that can divide the monotony upThere's a pretty big variety in army operations. Anything from convincing illiterate villagers that their hamlet being bombed is a good thing (Psychological operations) to basically playing videogames (Flying a drone).
4) Highschool setting also easily folds in peripheral characters like parents, teachers, and stuff who aren't necessarily the villains.This might be slightly iffy, but it's not just the enemy you have to deal with in war. You have refugees, black marketeers, intelligence agents with no discernible motive, high command, those assholes in the Air Force who never have to deal with our shit, etc, etc. There's a lot of options and not all of them are (necessarily) bad guys.
Plus, unlike college, a war with conscription is mandatory.
So let it be known that any high school drama could be transferred to a wartime setting and you wouldn't have to change much.