O'Brien's first published work was a war memoir and account of his year as a "grunt" in Vietnam, If I Die in a Combat Zone: Box Me Up and Ship Me Home (1973). This book begins probing the themes that dominate most of O'Brien's works, particularly the issue of moral courage. He followed up his autobiographical account with a debut novel entitled Northern Lights (1975), which posits two brothers against one another as foils — one brother went to Vietnam and the other did not. The crux of the novel, which is set in O'Brien's native Minnesota, is a cruel blizzard against which both brothers must struggle. Through this experience, the brothers learn more about each other, and their own motivations and values are illuminated in their own minds. This early work signals the reflection, self-reference, and thorough interior probing of characters that will become the hallmark of O'Brien's style.
O'Brien's next novel departs from the more traditional form of Northern Lights. Going After Cacciato (1978) is a more surreal and fantastical novel that brought O'Brien to wider public acclaim and earned him the 1979 National Book Award in fiction. A sort of dark, ironic comedy, the subject, an Army private, Cacciato, who catalyzes the story's action, deserts his unit in Vietnam and heads for the Paris peace talks. Literally walking away from the war, the other members of his unit are ordered to pursue him. The story is told from the point of view of Paul Berlin, the character that most resembles O'Brien, as they follow Cacciato across the world. O'Brien begins to push the limits of truth and believability in this novel as well as the bounds of temporality, both stylistic choices that reappear in The Things They Carried.
