We Don't Always Live Up to Our Reputation

This story about Operation Pastorius, which I got to via MetaFilter, describes how Germany forced some U.S. citizens to go on a mission to be saboteurs in the U.S. during WWII...but the fellows appparently agreed to go only to get away from Germany, and a couple of them defected immediately. The kicker is that they had a terrible time getting the FBI to believe them, and then Hoover betrayed the ones who defected, treating them as criminals. Furthermore, the ones who didn't defect hadn't actually done anything criminal...so the government put them in a military tribunal and had them executed. According to this account, this was mostly on Hoover.