Yeah, after he invaded Poland, he wanted to withdraw and invade it again. His generals talked him out of it. Just kidding. I've read a fair amount about Hitler, but I never heard that one.
There was some very interesting psychological analysis of Hitler in Robert Waite's "The Psychopathic God" and in Erich Fromm's "The Anatomy of Human Destructiveness." I think Fromm mentioned the repetition compulsion. That joke about Poland had a lot of truth behind it. Hitler invaded many OTHER countries after he invaded Poland, probably because he wanted to repeat the words, thoughts, and feelings he experienced the first time. Or was Czechoslovakia the first time?