With all these forces on the ground, it still took over 2.5 years for the allied forces to bring the war to Berlin. -- well, that's because the punch up from Italy is difficult -- Italy is difficult to conquer (and that's what the Romans also found out, it took them centuries) due to its mountainous nature
On the other hand, once you get east of the Rhine you are on the vast Eurasian flatland that extends all the way to the ural mountains
From the Rhine to the Volga, armies can walk across easily, there are just rivers that slow down armies, not mountains.
That's why this area has been a constant struggle between Germanics, Poles, Russians, Lithuanians, Mongols, etc.
Thanks for the additional comments Cronos. You touched on some informative points there. I agree.
The U. S. S. R. had it tough. It was touch and go for a while there, and the supplies really did arrive just in time for the U. S. S. R. to regroup and start taking it to the Germans.
I’ve read about the experiences with Russia against Germany, and it’s a tough read.