Because O'Brien starts with the war, we'll start there, too. First, some basic history:
If you don't know already, the Vietnam War was a Cold War conflict that began for obscure reasons. Technically, it was a civil war between North and South Vietnam. You probably want to go over to our US History Guides on Cold War: Causes and Origins" and "Vietnam War" to get all the details – it's a messy and complicated subject. After you browse those, come right back.
Hum-dee-dum…back? OK, so Vietnam had been colonized by the French in the late nineteenth century, but the French pulled out in the 1950s, and almost immediately thereafter, the war started. It lasted until 1975. American involvement happened kind of gradually, but the United States had soldiers over there helping out South Vietnam starting in the early 1960s. The Quang Ngai province, where O'Brien was a foot soldier, was a Viet Cong stronghold. The Viet Cong – and this is important – were not the North Vietnamese army, but a South Vietnamese guerilla outfit who were on the side of the North Vietnamese.
OK, we're going to stop the dry recounting of facts, now, because that's really all we need to get you oriented. The point is, the Vietnam War was an extremely unreliable animal, the American soldiers were aware of this, and O'Brien is an American author and veteran of the Vietnam War. The war began for reasons that were not clear, and the people that the American soldiers were supposed to be protecting kept trying to kill them. Nothing seemed to make sense. So you can see why O'Brien portrays the setting almost as another character. The men fight in the jungle, and because the Viet Cong could be watching them at any given moment, it seems as if the land itself is watching them. Black and white facts and "reality" are unreliable there.
Then there's small-town America. Before and after the war, America all about reliability – the opposite of Vietnam. A list of standard small-town features – A&W, Dairy Queen, movie theaters, skating rinks – pop up in stories set in both pre- and post-war times, showing the unchangingness of the place. Norman Bowker drives around and around the lake in his hometown (which, according to O'Brien in "Notes," is really O'Brien's hometown), and every time he goes around, the town is still the same. Before the war, in "The Lives of the Dead," the stasis of the town seems comforting, but after, in "Speaking of Courage," it's frustrating. Everything is absolutely, fixedly real. It's no wonder that O'Brien doesn't trust civilians to understand his version of truth.