It was reported that the Nazis had elaborate plans for “administering” the governments of the countries they defeated - including the United States. . . in print and divided up in black and white. If the Allies had lost that war, how horrible it would have been - and there were times they thought they might just lose it. Daddy was in the army infantry in Italy, marched into Berlin just half an hour after Hitler had committed suicide; he said there were times when the American soldiers thought they might not win that war - but, said they knew the HAD to win it anyway. When he came out of basic training, his observation was that they were ready to charge hell with a bucket of water.
There was a very interesting movie made in 1966, called “It Happened Here” which was a fictional account of what life might have been like in Nazi-Occupied Britain.