This novel offers two narratives. On the one hand, this story is clearly about this titular Cacciato, who has abandoned the war and whose pursuit keeps the characters occupied. But, on the other hand, there is the abstract journey that all the soldiers endure. They struggle to deal with their PTSD, having experienced severe horror on the battlefield. They want to find Cacciato for their military purposes, but their pursuit also symbolizes their internal journey.
Because of their experience of war, the soldiers experience chronic pain and discomfort in the form of paranoia, due to their PTSD. Therefore, they are at odds with themselves to find this man and return him to the battlefield; as they pursue him, they must also face that part of themselves which, like Cacciato, hates war and resents the damage done by war on their bodies and minds. They are trying to prevent someone from escaping, but they also crave escape.
Later in the story, we learn that the battalion undergoes a change of heart. There is confusion about whether Cacciato is allowed to escape or if they stop him, and there is further confusion about whether he is even alive. The reader learns a fascinating plot twist; perhaps Berlin killed Cacciato himself and invented the whole chase to throw the military off his tail, knowing that he committed a war crime. This is a symbol of their loss of innocence. They all "killed" Cacciato by overcoming their desire to escape war.
