Adolf Hitler's nephew fought in the US. Navy in World War II. But he had to get special permission from President FDR and from the FBI to do it. Hear about it at Urban Legends and Stranger truths. 80 years ago, adolf Hitler's half nephew enlisted in the US. Navy with the intention of combating the N*** regime. But it took a few attempts, which included a letter to President Franklin D. Roosevelt for William Patrick Hitler to get special permission to join the fight