I stood on a concrete platform, my elbows resting atop the high, thick, mud-brick wall that surrounded our rented house, on guard duty at our temporary base in the heart of the western Afghan city of Farah. With an M16 at my side, I was sweating and filthy under the murderous July sun, my bowels twisted by what my fellow soldiers called the “Farah flu,” but also by fear. I worried I would never see my wife, family, or small Iowa farm town again.

It was 2004, early in America’s war in Afghanistan. The memory of the Sept. 11 attacks burned more sharply in those days, and I resented the orders that confined my infantry unit to a reconstruction mission. I wanted to seek and destroy the evil Taliban, the allies and sometime hosts of those who had contributed to the murder of nearly 3,000 innocent people on 9/11.