According to this article, "During the spring of 1972, in the mist of the Vietnam conflict, Ripley found himself in a desperate situation. More than 30,000 North Vietnamese troops were pushing through defensive points during a major assault when Ripley put himself in personal danger to set high explosives and destroy a key bridge in Dong Ha. This single act of bravery thwarted the North Vietnamese troops assault and destroyed 200 of their tanks in the process. Ripley later received the Navy Cross, the nation's second highest award for heroism, for his personal sacrifices in the line of duty."
Ripley's orders that day: "Hold and die."
"When the timed-fuses detonated, Ripley – running for his life on the road leading away from the bridge – was literally blown through the air by the massive shockwave he had engineered. The next thing he remembered, he was lying on his back as huge pieces of the bridge were hurtling and cartwheeling across the sky above him."