There's an unremarkable door in an unmarked building in a regular military base it doesn't matter where in the world. Behind that door they keep in storage a three-hours slice of war. It's too fragile to be moved out of the room: when a soldier has to look at it for training or punishment they have to cross the door, sign the consent forms, and sit on a chair where a hollow-eyed nurse will hook a dozen tubes and wires to their bodies. The nurse doesn't leave the room although it's obvious they would want to.
Three hours later the soldier leaves the soundproof room. Never a minute earlier no matter what. They take with themselves the end of good nights; eyes continuously scanning the sky for death; a cautiousness around corners; the stretching of seconds to nightmares; a grief the size of the world; the visceral unreality of any aspiration further away than cover and water and enough food to survive.
Some people remain functional, resign, break down. One or more, in any order. What nobody does is go back to the room with the chair and the wires between it and the small bed where a child sleeps who will never wake up behind an unremarkable door in a long hallway filled with identical ones and a discrete sign abeled "Archive."