The German High Command was starting to wonder why the RAF was so good at shooting down their planes. It was almost as though the British had some device that told them where in the sky airplanes were! So to avoid the Germans' discovering that the British had a functional radar system, I believe the first in the world, they published all these stories about how much carrots improved the eyesight of their pilots. Now, in reality, you could eat carrots until you turned orange with carotenosis, and it wouldn't actually make your eyesight one whit better, but the Germans still fell for it, and the radar installation remained a British secret.