To have participated in Operation Overlord, the Allied invasion of Normandy in World War II, now that’s something. To have waded ashore through a deathly brew of bullets, blood and floating bodies, well, that’s a feat of a totally different stripe. But to have been a Navy frogman, the first to touch beach the morning of June 6, 1944, that’s the stuff legends are made of. A forerunner to the Navy special operations force known as the SEALs, Naval Combat Demolition Units cleared the way for the initial invasion force on that historic day. "There was stuff blowing up all...