War against one's will
This memoir starts with a portrait of systemic injustice. Because of the draft, O'Brien is forced to participate in a war that he resents on moral grounds. For his own survival, he must fight against an enemy that he doesn't really want to kill. The allegory points to the injustice of the Vietnam War, because the government's motives for the war were historically very dubious, and the popular opinion didn't matter, because the government just drafted soldiers against their will under the threat of serious consequences. Almost 60,000 Americans died in Vietnam.
Escape and survival
Throughout the novel, the reader sees a character absolutely perplexed by the threat of death and torture. The army keeps them in under threat of serious criminal charges, sentencing innocent young men to death. This leads to a motif through which O'Brien analyses his options. He wants to survive. He wants to escape. He is reduced to his animal instincts for survival, but the war machine keeps him involved against his will. He is tortured by his own government and goes through the escape plans to no avail.
Loneliness
The problem of loneliness begins to emerge as an archetypal battle throughout the course of the plot. First, he is removed from his community. Then he is shown by consistent relocation that he cannot become attached to anyone. Also, when he becomes attached, he risks emotional devastation in the case that someone dies. By the end of this symbolic journey, he realizes the truth about loneliness: when he gets home (if he gets home), no one will ever understand what he has endured, and it is too complex and sublime to share.
Investigation as a symbol
When O'Brien is moved to a legal investigative team, he is finally allowed to serve a role he appreciates. He is charged with investigating the My Lai Massacre for signs of illegal activity. The US government is concerned with how the military handled that conflict, and O'Brien plays the symbolic role of truthful learner. This sets him on a path in life, to tell the truth about Vietnam, and it symbolizes his new role in life as a martyr who can share what he witnessed. The symbolic role shows him a path in life.
Emotional hell
Throughout the story, O'Brien becomes more and more emotionally distraught, such that when he is sent home, the residual damage of his psyche lingers. He sees that the veterans are in hell, even when they return home, because the weight of their actions hangs on them like an albatross. They are both agents of government injustice (because O'Brien knew the whole time that the war was morally wrong in his opinion), and the victims of it (because they were fighting for survival and did what they had to to survive without their own government destroying their lives if they tried to disobey).
