As Capt. Tom Davis stands at the tailgate of the military cargo plane, the night air sweeps through the hold. His eyes search the black terrain 1,200 feet below. He grips the canvas of his reserve parachute and takes a deep breath. Davis and the men who make up his Special Forces A-team are among the most highly trained soldiers in the U.S. Army. It's 1972, and Davis isn't far removed from a tour in Vietnam, where he operated along the Cambodian border. His communications sergeant served in Command and Control North, which was responsible for some of the most...