Two days later, a front moved in, the sky became mostly cloudy, and Bischoff made the mistake of relaxing. Another Catalina found them: this one used the clouds to conceal his approach, waited until U-691 was crossing a patch of sunlit water, and then dove, centering his own shadow on the U-boat’s bridge. Fortunately, Bischoff had double sun sector air lookouts. This was a jargonic way of saying that at any given moment, two shirtless, stinking, unshaven, sunburned men were standing on the deck, casting shadows over their eyes with their outstretched hands. One of these men said something in a quizzical tone of voice, which alerted Bischoff. Then both lookouts were torn apart by a rocket. Five more of Bischoff’s men were wounded by cannon fire and rockets before Bischoff could get the boat under the surface.