Germany invaded the Soviet Union in June 1941. German propaganda portrayed the war against the Soviet Union as both an ideological war between German National Socialism and Jewish Bolshevism and a racial war between the Germans and the Jewish, Romani and Slavic Untermenschen ("sub-humans"). Local populations in some occupied Soviet territories actively participated in the killing of Jews and others, and helped identify and round up Jews. German involvement ranged from active instigation and involvement to general guidance. In Lithuania, Latvia, and western Ukraine, locals were deeply involved in the murder of Jews from the beginning of the German occupation. Some of these Latvian and Lithuanian units also participated in the murder of Jews in Belarus. In the south, Ukrainians killed about 24,000 Jews and some went to Poland to serve as concentration and death-camp guards. Military units from some countries allied to Germany also killed Jews. Romanian units were given orders to exterminate and wipe out Jews in areas they controlled. Ustaše militia in Croatia persecuted and murdered Jews, among others. Many of the killings were carried out in public, a change from previous practice.
In his bunker, in the Chancellory building in Berlin, knowing that the war was lost and that the “1,000 Year Reich” had lasted only a few years, Hitler committed suicide hours after marrying Eva Braun. Germany formally surrendered to the Allies on May 7, 1945. By the end of the war, more than 55 million had died and 35 million wounded. Only 17 million of the dead were soldiers.
Before the war, Mengele had received doctorates in anthropology and medicine, and began a career as a researcher. He joined the Nazi Party in 1937 and the SS in 1938. He was assigned as a battalion medical officer at the start of World War II, then transferred to the Nazi concentration camps service in early 1943 and assigned to Auschwitz, where he saw the opportunity to conduct genetic research on human subjects. His subsequent experiments focused primarily on twins, with little regard for the health or safety of the victims.