Apparently he didn’t agree with using his rockets as a military tool. Was actually locked up by the Nazi’s and bizarrely released by Hitler - who being such a dumb arse probably thought he was related to Eva Braun... Post war he did work in America - like a lot of scientists liberated from the axis of evil. There were some highly dodgy scientists though, like those from Unit 731 who got immunity. Wankers. Sorry derailed...