They broke the back of the german army with the big help of the US who sent millions of tons of materials, weapons etc. to Russia.
It is a shame that the russian war criminals, criminals against humanity were also judges at the trial of Nurenberg instead of sitting near the german criminals. 
Today we see the non-stop mistakes  the west has done  from 1945 to today and we are going to pay the price, especially Europe. 
I guess in the next few years a war NATO vs Russia will start or at least Europe vs Russia if the US will leave Europe alone to face Russia.