Based on the memoir American Sniper: The Autobiography of the Most Lethal Sniper in U.S. Military History (2012) by Chris Kyle, with Scott McEwen and Jim DeFelice. Kyle, who became the deadliest marksman in U.S. military history with 255 kills from four tours in the Iraq War, 160 of which were officially confirmed by the Department of Defense. While Kyle was celebrated for his military successes, his tours of duty took a heavy toll on his personal and family life.