I am reading a very interesting book ("In the Garden of Beasts") about the early days under Hitler. It mentions how the language used by Hitler and other Nazis changed during that period and became "weirdly inverted." For example, fanatical became positive to mean a "happy mix of courage and fervent devotion," such as a "fanatical animal lover." But also some very old words were brought back, such as ubermensch and untermensch. New words such as strafexpedition, meaning punitive expedition, came into being.

I hadn't heard about this before, but of course it makes sense. Do you know any examples?

You might want to read Victor Klemperer's LTI – Lingua Tertii Imperii (LTI - Language of the Third Reich). He was a German-Jewish professor of literature and literary critic. (He came from aprominent family: his brother was the conductor Otto Klemperer and his nephew Werner Klemperer was an actor, probably best known for playing Colonel Klink on Hogan's Heroes). The Wikipedia article on the book (link) has some examples.

(BTW, I, too, am reading In the Garden of the Beasts. It's great.)

Oh, thanks, I will read it. It is really interesting to think the language even changed during that time. I wonder if that happened during other wars.