More than 50 years after he hung beneath a bridge under enemy fire to stop a North Vietnamese armored invasion, the heroic actions of John Ripley are set to be recognized with the nation’s highest award for valor. As North Vietnamese tanks massed on the far side of the river in 1972, Ripley climbed onto the Dong Ha Bridge carrying explosives — knowing that if the bridge stood, the invasion could roll south. During the opening days of the Easter Offensive, Ripley hung from the steel girders of