re: When did the German soldiers of WWII realize they were the 'bad guys'?

I recently read Shadow Divers about the missing U Boat found in New Jersey Waters. Towards the end of the book they did an overview of the lives of the crew. The officers all hated Hitler with a passion for what he had done to the country. They were just all to scared to say anything to one another or each other because they didn't know who to trust. They were all just doing their duty for their country. It really got me interested in this very subject.