Final answer:
The Einsatzgruppen were specialized Nazi units responsible for the systematic murder of Jews, Roma, and political opponents during World War II, leading to mass shootings and the development of gas vans and extermination camps.
Step-by-step explanation:
The purpose of the Nazi Einsatzgruppen was to carry out mass executions of Jews, Roma, and perceived political enemies, primarily in the territories occupied by Germany during World War II. These mobile killing units followed the German army, particularly during the invasion of the Soviet Union in 1941, and were responsible for the mass murder of countless civilians. Victims were typically rounded up, forced to hand over valuables, taken to secluded areas, and shot, often after being made to dig their own graves. This tragic period of history showcases the brutal efficiency and scale of the Holocaust, which is sometimes referred to as the 'Holocaust by bullets.' Mass shootings by the Einsatzgruppen revealed the psychological toll on the soldiers, leading to the use of gas vans and later, the establishment of extermination camps such as Auschwitz where gas chambers using Zyklon B were employed.