Joan Pujol, a Spanish spy acting as a double agent, but loyal to the allies, convinced hitler that the D-Day was a diversion. His story is unbelievable and I recommend that everybody checks it out. The nazis were so close to stopping D-Day and this foreigner convinced them otherwise.

Oh and he made the nazis fund a spy group which did not exist. He forged travel expenses and reports and made the nazis pay for like a dozen people’s salaries.

Incredible story: en.wikipedia.org/wiki/Juan_Pujol_García