American Sniper opens with a depiction of events that took place late in March of 2003. As a member of SEAL Team 3, Chris has been assigned to protect Marines as they move through a small Iraqi town; he is not yet a certified sniper, but his job for the time being is to spot and eliminate targets. The only people in sight are a woman and a few children, but it quickly becomes apparent that the woman has a grenade. Chris takes a shot and hits her, preventing her from attacking the troops. This would be his only kill that did not involve a male combatant.

Chris explains his duties in combat: it was up to him to protect other members of the American armed forces from their enemies in Iraq, enemies who had no regard for human life and were the embodiment of evil. Killing such ruthless enemies was necessary, but Chris is uncomfortable writing about his life. As a sniper, he registered approximately 160 kills, according to the official number; he credits many of these to factors such as good training and the opportunity to be in combat often, not to anything that made him “better” than other servicemen.