That's not quite how it went down - the really top guys were running the show in Nazi Germany until the very end, and only came to the US after Germany lost the

That's not quite how it went down - the really top guys were running the show in Nazi Germany until the very end, and only came to the US after Germany lost the war. See siblings comments about Mittelwerk, eg. Also Chabon's (fictional) novel Moonglow covers some of this history well.