With the start of the second World War and a swift succession of German victories, the Nazi regime began realizing its longstanding goal of territorial expansion. Under conditions of war and military occupation, they could pursue racial goals with more radical measures. The German Army, military, SS, and German police units took an active part in authorized mass murders of Jews in the Soviet Union. The Germans and their collaborators deported roughly 2.7 million Jews and others from occupied Europe to killing centers in German-occupied Poland. At the largest of the camps, Auschwitz-Birkenau, transports arrived from all across Europe. The camps of Majdanek and Auschwitz were the first liberated, as Soviet troops reached Poland. As more Allied soldiers saw the camps with their own eyes, the truth was undeniable. Part 4 of 4 of this video series.