All his life, Greg McPartlin wanted to be a Marine corpsman, a medic skilled at saving lives. Three months of "bagging-and-tagging" bodies during Vietnam's Tet Offensive took the luster off being a Marine-but not off McPartlin's desire to serve his country. After assisting in the sea-recovery of Apollo 11-the first ship to bring men to the moon-the twenty-year-old McPartlin was redeployed to Vietnam as an elite Navy SEAL. Barred as a medic by the...