The U.S. expanded due to them winning the war
Which war? WWI: We were isolationists until illegal German U-boats sank a United States commercial ship called the Lusitania.
WWII: We were isolationists until December 7, 1941 when the Japanese air fleet surprise attacked and bombed us at Pearl Harbor.
The Nazis were able to control people from 1933 to 1939 because that was the begin of the events leading up until the Holocaust. Where they had tried to get rid of all the Jewish people in Germany.
I am not 100% sure but I believe this is why ^-^