They were worried for good reason. With so many troops and so much artillery swelling in England, it was impossible to keep the attack a secret. Hitler knew it was coming, and he’d been preparing a defense for months. Only one detail eluded him, and he was confident in a Nazi victory if he could figure it out—he needed to know where, exactly, the attack would happen. To make D-day a success, the Allies needed to keep him in the dark: They’d have to trick the Germans into thinking the real invasion was just a bluff, while making it seem like a major attack was imminent elsewhere. The task seemed impossible, but luckily, the British had a secret weapon: a short, young balding Spaniard. He was the king of con men, an amateur spy gone pro, the world’s sneakiest liar. He was also, of all things, a chicken farmer.

Mental Floss