Propoganda (look at posters, etc). He made them out that culture to be nasty, big nosed, corrupt. Which for some familes of that culture is true. Basically by that culture doing those corrupt acts it just reinforced his propoganda.
Just listen to these soldiers to see what I mean about how they were affected by the propoganda and how they viewed Stalin, etc.
Not hard to understand how it got so big. They thought they were removing the world of evil that would hurt people of their own country. Probably not far from the truth
, but wrong way théy did it.
Allies used reverse propoganda stating they were that, evil.
Both sides think are doing right in their own way.
Allies just had more men, resources is to why they won.
Same propoganda being used in the US elections, etc. Just some might not notice it.