DAVE EUBANK MAKES an exploding gesture with his fist to alert the guerrilla soldiers following him of the danger ahead. “From here until we pass the road, the trail is lined with mines,” he says, scanning the mountainous Burmese jungle for signs of trouble. “Watch where you step.” As his signal relays down the line, conversations fall silent and the air hums with only the sound of heavy breathing and hundreds of footsteps on hard-packed ground. Eubank picks up the pace, slashing through brush and thorny stalks that tear at his clothing. A former U.S. Special Forces officer and ordained...