Originally posted by jack merchant
Well, if you're referring to the Wannsee conference where the Endlösung was formally adopted as policy, I think that happened in January 1943. However, the evilness of the Nazi Reich was apparent well before that, as camps for political dissidents, Jews and the mentally ill were set up much earlier (Dachau in 1937, iirc) and the persecution began almost right after Hitler became Reichskanzler. Not to mention the Einsatzgruppen who committed innumerable acts of mass murder after the invasion of Russia.
And that's even without mentioning the Nazi pioneering of terror bombing as a means of war in Guernica, Rotterdam and the Blitz.
The point is, Britain and France may not have fully realized how evil Hitler truly was when they declared war in 1939 (over the unprovoked invasion of Poland - rather a good casus belli imho) but the threat he represented to freedom was apparent enough.
Which is why Casablanca was fully justified in glorifying the Free French, imho. In the context of the time, colonialism wasn't as discredited as it is now (otherwise, the British should have been portrayed less kindly there and in other movies, too).