Nearly nine-tenths of US adults are probably unaware that 20m Russian soliders died in WWII.
https://en.wikipedia.org/wiki/Katyn_massacre
Btw Russians have a funny way of counting WW2 casualties, they include Poles killed by Russians as Russian victims due to annexation of Poland by Russia post ww2. https://en.wikipedia.org/wiki/World_War_II_casualties_of_Pol...
Casualties (source: Wikipedia)
3,436,066 USSR, Battle of Leningrad
1,129,619 USSR, Battle of Stalingrad[1]
1,076,245 US, all battles (europe + pacific)
[1] a crucial battle:
https://news.ycombinator.com/item?id=23612474