“I am sending you out like sheep into the midst of wolves, so be wise as serpents and innocent as doves. (Matthew 10:16) After the 2003 invasion of Iraq toppled the strong-arm government of Saddam Hussein, the country fell into a chaotic and violent insurgency. Multiple factions fought against each other, the coalition forces, and the emerging government. The U.S. military transitioned to stability and counter-insurgency operations shortly after the Ba’athist regime fell. Service members patrolled the streets, worked to restore essential services, and tried to create an effective government. In this context, Marine General James Mattis is reported to have told his Marines, “Be polite, be professional, but have a plan to kill everybody you meet.” That might be understandable in the midst of a violent insurgency when it’s hard to tell friend from foe, but it is a horrible way to live your life. The phrase my colleagues used during this time was, “Keep...