In Superman 226, an Infinite Crisis Crossover title, Superman is reliving his life as a Superman from an alternate earth smacks him around. During these flashbacks Superman tries to stop Hitler but cannot. Something about Dr. Fate and Hitler possessing the Spear of Destiny.
Flash forward a few years and Superman is fighting no greater a foe then ... Wait for it ... The United States of America. Why, you ask? Because, a thought bubble tells us, "The witch hunts have begun." In this rendition of Congress's investigation into Communist spying on American soil, the Justice Society of America has been hauled before the Congress and ordered to remove their masks. Never mind that half that folks standing there aren't wearing any masks. Superman makes his grand entrance to call a halt to this outrage.
In case you failed to get the analogy between the America during the 50s and Nazi Germany, the writers spell it out for you. In a full page panel Superman stands before an empty concentration camp and cries out, "NEVER AGAIN." As Superman flies into Congress during hearings on Communist Spies in America, his thoughts are "NEVER AGAIN." Being asked to testify before Congress on Communists in America is no different than being in a Nazi Concentration Camp.
Nick Newman gives us the following in his review in the "Mild Mannered Reviews" section of the Superman Homepage :
My favorite part was definitely the World War II scenes though. I've always liked the idea of tying the heroes into the conflict, and watching the whole JSA go to war is a great concept. The holocaust page was also very appropriate, and very in key with the Earth-2 Superman.
I also loved the scenes with the JSA standing up to congress (if you haven't read The Golden Age, by James Robinson, go do so now... I'll wait) and Superman standing up to congress was great.