"...spools of suffering set out in ordered rows"
-> metaphor - describes photographs through pain and trauma as if the images haunt him. ~ speakers PTSD even if he is only a spectator not a soldier.
-> "spools" ~ shows extent and of magnitude of suffering that he witnessed.
-> sibilance ~ creates sinister atmosphere emphasising his distress. -- he craves peace and silence after the scenes of violence he witnessed.
-> "ordered" juxtaposes the chaos - desperate to gain control and order back on his emotions