Many students are assigned Tim O'Brien's The Things They Carried, and students who know that novel will notice some obvious similarities. For one, they both share war stories in the order they are remembered, not in the order that the warfare actually happened. Often, other points of view are spliced into the speaker's memory, as if they have been carrying other people's burdens within their own trauma. For instance, a person who sees another person blown up by a bomb can never un-feel the traumatic moment, and it might even feel like they blew up too. The effect is that The Sorrow of War is a formidable account of PTSD and the way the mind processes trauma.
Kien's story leaves no two ways about it. The speaker witness horrifying visions. The opening section of the novel is essentially the permanent feeling of panic that has haunted Kien his whole life. It's perfectly depicted in that the soldiers (who had good reason to believe they were going to be executed by the enemies) find out that the war has ended, and now they must collect the remains and corpses of their fallen brothers. The nightmarish image is complete with the soldiers' attempts to distract themselves from the lingering effects of trauma. It seems they can't un-see the battles, and Kien feels as though he's been cleaning up corpses for a long time.
In some ways, this novel is Kien's account of what it was like to be at war (which he says is his goal in the novel), and that is done through Kien's willingness to share other stories from people he knew or heard about. When Bao joins the novel at the end, the implication is that the stories that were shared have true origins. In other words, there are elements of the novel that are fictionalized, but the horrifying scenes of the battlefield are real.