An urban legend says eating large amounts of carrots will allow one to see in the dark. The legend developed from stories of British gunners in World War II, who were able to shoot down German planes in the darkness of night. The legend arose during the Battle of Britain when the RAF circulated a story about their pilots' carrot consumption as an attempt to cover up the discovery and effective use of radar technologies in engaging enemy planes, as well as the use of red light (which does not destroy night vision) in aircraft instruments. It reinforced existing German folklore and helped to encourage Britons—looking to improve their night vision during the blackouts—to grow and eat the vegetable.
That is awesome. Excellent use of propaganda, Brits.