Since the U.S. invasion of Afghanistan, 42 American soldiers have been killed in the desolate Korangal Valley, which serves as a relay point for Taliban forces traveling between Kabul and the Pakistan border. This documentary by Tim Hetherington and Sebastian Junger covers the 15-month deployment there of a platoon whose rocky outpost (named Restrepo for one of their dead comrades) was the target of endless enemy attacks, and it’s an essential record not only of the Afghanistan conflict but of men in battle. Interview sequences with the surviving soldiers, shot in Italy after the deployment, connect the verite video footage and reveal the psychic trauma these hardened warriors will carry around for the rest of their days. (When one them recalls a horrific firefight, his voice trails off and his eyes glaze over as the memory takes him away; the video we’ve seen earlier of that chaotic engagement is as close as any journalist could possibly get to what happened.) The movie premiered in January 2010 at the Sundance Film Festival, too soon to include a tragic denouement: in April the U.S. command surrendered the Korangal Valley to the Taliban.