O’Brien says the most enduring Vietnam stories are those that are between the absolutely unbelievable and the mundane. Rat Kiley, who has a reputation for exaggeration, tells a story of his first assignment in the mountains of Chu Lai, in a protected and isolated area where he ran an aid station with eight other men near a river called the Song Tra Bong. One day, Eddie Diamond, the highest ranking man in his company and a pleasure-seeker, jokingly suggests that the area is so unguarded and seemingly safe that you could even bring a girl to the camp there. A younger medic, Mark Fossie, seems interested in the idea and goes off to write a letter. Six weeks later, his elementary school sweetheart, Mary Anne Bell, arrives, carried in by helicopter with a resupply shipment. Fossie explains that getting her to camp was difficult but not impossible and for the next two weeks, they carry on like school children. Mary Anne is curious and a fast learner—she picks up some Vietnamese and learns how to cook. When four casualties come in, she isn’t afraid to tend to them, learning how to repair arteries and shoot morphine. She drops her fussy feminine habits and cuts her hair short.
After a while, Fossie suggests that Mary Anne think about going home, but she argues that she is content staying. She makes plans to travel before she and Fossie marry. She begins coming home later and a few times not at all. One night she is missing, and when Fossie goes out looking, he discovers that she has been out the entire night on an ambush, where she refused to carry a gun. The next morning, Fossie and Mary Anne exchange words and seem to have reached a new understanding. They become officially engaged and discuss wedding plans in the mess hall, but over the next several nights it becomes clear that there is a strain on their relationship. Fossie makes arrangements to send her home but Mary Anne is not pleased with the prospect—she becomes withdrawn, and she eventually disappears.
Mary Anne returns three weeks later, but she doesn’t even stop at her fiancé’s bunk—she goes straight to the Special Forces hut. The next morning, Fossie stations himself outside the Special Forces area, where he waits until after midnight. When Kiley and Eddie Diamond go to check on Fossie, he says he can hear Mary Anne singing. He lunges forward into the hut, and the two others follow. Inside they see dozens of candles burning and hear tribal music. On a post near the back of the bunk is the head of a leopard—its skin dangles from the rafters. When Fossie finally sees Mary Anne she is in the same outfit—pink sweater, white blouse, cotton skirt—that she was wearing when she arrived weeks before. But when he approaches her, he sees a necklace made of human tongues around her neck. She insists to Fossie that what she is doing isn’t bad and that he, in his sheltered camp, doesn’t understand Vietnam.
Kiley says that he never knew what happened with Mary Anne because three or four days later he received orders to join the Alpha Company. But he confesses that he loved Mary Anne—that everyone did. Two months after he left, when he ran into Eddie Diamond, he learned that Mary Anne delighted in night patrols and in the fire. She had crossed to the other side and had become part of the land.
In this story, O’Brien paints a highly stylized version of Vietnam as a world that profoundly affects the foreign Americans who inhabit it. He portrays a stark difference between the native world of Vietnam and the world of the Americans. Mary Anne Bell fully embraces Vietnamese culture, while Mark Fossie ignores it. The difference between their experiences sets up a world in which the separate cultures are completely foreign to, and incompatible with, each other. O’Brien does not suggest that one can assimilate elements of each culture into a comfortable mix. Rather, the characters must choose a single cultural identity.
“Sweetheart of the Song Tra Bong” refutes the idea of women as one-dimensional beings who serve only to offer comfort to men. Fossie assumes that if he brings Mary Anne over to the relatively comfortable quarters he and his men keep, he will gain her comfort and companionship and she will remain unaffected by her surroundings. This fantasy is immediately shattered as Mary Anne is instantly curious about the things surrounding her—from the language and the locals to the ammunition and the procedures and finally the nature of war itself. The irony of this story is that Mary Anne’s new reality agrees with her, perhaps more than her conventional life. She is enlivened and empowered by war: its influence prompts her to make plans for future travel and to attempt to steer her path away from the life she earlier considered desirable. Ironically, although her soldier boyfriend brings her over to be a comfort while he is in the midst of war, in the end, Mary Anne’s conversion makes her hungrier for adventure than he is.