Ben Fountain's Billy Lynn's Long Halftime Walk: A Novel follows soldier Billy Lynn on his victory tour while showing the readers how he now views, essentially, war (or, conflict). After the events that took place at Al-Ansakar Canal, Billy's view on the war has turned into that of bitterness.
Once one partakes in gunfire and the death of a friend in one's own arms, we can certainly imagine the ensuing toll on that person. In this case, Billy lost his comrade - who goes by the nickname Shroom - while trying to save him from the gunfire.
Billy jumped in and tried to retrieve him but Shroom's eyes were "zeroing in on Billy with such insurgency, with so much pressing news, then the fade and his soul releasing, whoom, as if the life force is a highly volatile substance, contents stored under pressure" (Fountain, 2012).
The fact that Billy explained Shroom's death in such a manner clearly exemplifies the effects of, obviously, death right before your eyes and seeing the light go out in someone else's eyes is traumatic in its own right.
Side note: This story was absolutely terrible and one of the worst books I have ever read. I had a hard time trying to figure out if the point of the story was to see if Billy would get laid by Faison (the cheerleader) or actually focus on things like PTSD, anxiety, and I truly don't think that the author did much in that realm.
Instead, it felt more like I was reading a cheesy teenage romance novel with a hint of military experiences (i.e. military romance book but the only thing military-relevant is Billy and his Squad at the Texas Stadium). Fountain, B. (2012). Billy Lynn's Long Halftime Walk: A Novel. HarperCollins.