Matthew Reilly's roundabout journey to college took a painful, decisive turn after a nighttime crash in Iraq. In 2008, six months into his first combat tour with the Army, Mr. Reilly and nine soldiers from his platoon were pursuing an insurgent when their armored fighting vehicle slammed into a roadblock. It was 2 o'clock in the morning, and fresh snow blanketed the ground. To avoid detection, the troops had been traveling without lights. Only the driver wore an infrared device to maneuver the hulking, eight-wheeled Stryker through the darkness. Barricades were a common tool of local insurgents. Sometimes the obstructions were explosive. Mr. Reilly had been riding in the rear hatch as a lookout. On impact, he snapped back, then whipped forward and smacked his head on a gun mount. He suffered a traumatic brain injury, tore his rotator cuff, and, as he now says with clipped efficiency, "demolished" his back. Seven discs from his lower back to the base of his spine were ruptured or herniated. Were it not for a can of grenades that had partially blocked his movements, Mr. Reilly would have severed his spinal cord. In this article, the author describes how Mr. Reilly, living with injuries, aimed to help other veterans.