@Alan McDougall,
I'm reading a book right now by Antony Beevor called "Vasily Grossman: A writer at war". (Antony Beevor wrote two of the best books I've read about WWII, "Stalingrad" and "The Fall of Berlin")
Vasily Grossman was a Soviet war correspondent who covered the entire war in Eastern Europe. He covered (and survived) the initial massive German invasion, the defense of Moscow, the Battle of Stalingrad, the Battle of Kursk, the discoveries of the Majdanek and Treblinka death camps, and the Battle of Berlin. His notebooks would have gotten him executed if the NKVD had ever discovered them, and as such he is one of the greatest sources of info about the war in the east.
One interesting point is the famine in Ukraine that Stalin had unleashed in the 1930s by collectivizing agriculture. About 7 million people died, they were reduced to cannibalism, etc. (No one knows if the famine was intentional or if it was just one of the greatest examples of brazen neglect in world history). It turns out that Stalin's propaganda team found a way to blame Jews for the famine.
Thus, Grossman discovered, the people in Ukraine not only greeted the Nazis as liberators but also helped them root out and exterminate the Jews. (Something very similar happened with the German invasions of Belarus, East Prussia, the Baltic states, etc). Of course the Germans created a famine of their own by utterly pillaging the conquered territories, and committing widespread atrocities against the general population, so "liberated" isn't exactly what Ukraine experienced.
But it just supports the point that the Eastern Front in WWII was not just a Hitler parade. It was sort of the culmination of a massive civil war in Eastern Europe that had been going on since the beginning of hostilities in the
First World War. The scale of the bloodshed and atrocities was possible only because of so much kindling on the ground.