Twenty seconds of raw terror ensue. U-691 is screaming across the surface, banking like a Messerschmidt as shells pound into the water all around her. Crewmen are spilling out of her hatches, looking like prison camp inmates in the bright sun, trying not to slide off the deck as it tilts this way and that, diving to snap the carabiners of their safety lines onto cables before they are blown out of their shoes by the waterspouts from the exploding shells. They are manning the guns.