Himmler ordered the closure of ghettos in Poland in mid-July 1942; most inhabitants were sent to extermination camps. Those Jews needed for war production would be confined in concentration camps. The deportations from the Warsaw Ghetto began on 22 July; over the almost two months of the Aktion, until 12 September, the population was reduced from 350,000 to 65,000. Those deported were transported in freight trains to the Treblinka extermination camp. Similar deportations happened in other ghettos, with many ghettos totally emptied. The first ghetto uprisings occurred in mid-1942 in small community ghettos. Although there were armed resistance attempts in both the larger and smaller ghettos in 1943, in every case they failed against the overwhelming German military force, and the remaining Jews were either killed or deported to the death camps.
After the German invasion of Czechoslovakia in 1939, the Nazis sent many thousands of Czech Jews to ghettos in Poland, Lithuania and Latvia. On 22 June 1941, the German invasion of the Soviet Union brought many more Jews within the German sphere of influence. Some Polish Jews had managed to escape into the Soviet Union during the German invasion of Poland. Now, as the German army rolled into the Soviet Union, they were again trapped.
Mengele was born on 16 March 1911 to Walburga (née Hupfauer) and Karl Mengele in Günzburg, Bavaria, Germany. He was the oldest of three children; his two younger brothers were Karl Jr. and Alois. Their father was founder of the Karl Mengele & Sons company, producers of farm machinery. Josef was successful at school and developed an interest in music, art, and skiing. He completed high school in April 1930 and went on to study philosophy in Munich, where the headquarters of the Nazi Party were located. In 1931, Mengele joined the Stahlhelm, Bund der Frontsoldaten, a paramilitary organization that was absorbed into the Nazi Sturmabteilung (Storm Detachment; SA) in 1934.