Forward Operating Base Falcon is a miserable, hot, dusty outpost on Uday Hussein’s former estate in Arab Jabour, which lies along the banks of the Tigris River southeast of Baghdad. Sometimes, when Sergeant Scott Lange Kirkpatrick, 26, spent his nights here in a tent by the old stables with 49 other soldiers, the heat was so bad that he’d pull his cot outside and sleep under the stars. There was limited access to phones, no air conditioning, and none of the Green Zone amenities that could distract U.S. soldiers from feeling that things in 2007 were about as bad as they could get in Iraq. In the morning, he’d strap on 75 pounds of gear and lead his company of newly deployed “cherry” privates on white-knuckle raids and patrols through an area that was considered one of the most dangerous in the country.

Sometime in early summer, sick and on the verge of dehydration from a day under the searing sun, Kirkpatrick was leading a patrol in a far-off sector when, stopping to check a map, he heard a car approaching. It was after curfew, and no one should have been on the road. Then he heard the engine being gunned, and the car tore around the corner and headed straight for Kirkpatrick’s patrol. In such a situation, soldiers are required to fire a warning shot first, then shoot into the radiator. If that proves ineffective, they are then permitted to target the person behind the wheel. Kirkpatrick followed procedure. The car kept coming. So Kirkpatrick squeezed the trigger of his black M16 rifle one last time, and fired a round into the driver. The car skidded out of control and slammed into a wall—its occupant slumped over the wheel, dead. Scott Kirkpatrick had just killed a man.

Then he fainted.

It was five minutes to midnight on October 15, 2003, when Kirkpatrick sent an e-mail to his family and friends that would leave them dumbfounded. They knew him as the skinny shit-talker, the liberal idealist—the poet who stayed up all night listening to the Melvins, reading Philip K. Dick, and scrawling verses he’d belt out at poetry competitions. He was six feet tall and 165 jagged pounds of caffeine, Camel Lights, and sarcasm. A 22-year-old with a mop of dyed blond hair and an unkempt beard tends to stand out in the muted suburb of Reston, Virginia—a half-hour west of the nation’s capital.

So it was a shock to Kirkpatrick’s friends and family when they opened their in-boxes to find a carefully composed message detailing his plans to join the military.

“After nearly a year of thought and much deliberation I have decided to enlist in the US Army,” it read. “No one should think I have gone off the deep end and become some sort of right-wing radical hell bent on making war with everyone on the planet. I am still as independently liberal as I have always been, but these are questions of security and foreign policy, and I simply think the world has changed and it is time to adapt.”