The French naval bases at St. Nazaire and Lorient, occupied by the Germans in June 1940, quickly became the homes of massive U-boat fortresses—nearly indestructible submarine pens, built by mostly slave labor. The Royal Air Force began an all-out bombardment of the two ports. Despite their extensive efforts—and those of the Americans who joined them in 1942—the fortresses would survive, surrounded by the decimated French towns and countryside. This is the story of what was, perhaps, the longe