The horrors of the extermination camps, such as Auschwitz-Birkenau, are what most people primarily associate with the Holocaust. However, the attempt to murder all the Jews in Europe began with mass shootings outside the camps, on the Eastern Front, after the Nazi invasion of the USSR in June 1941.
The Einsatzgruppen (‘task forces’ – but in this context, mobile killing units), followed the German army as they invaded the Soviet Union - today's Belarus, Ukraine, and the Baltic states. Units were made up of SS soldiers and police. They were tasked with killing racial or political enemies by mass shootings. They massacred entire Jewish communities, and also killed communists, Roma, and residents of institutions for the mentally and physically disabled.
Jews in a town or city were marched to pits outside the settlement, where they were systematically shot. The most notorious of these atrocities was at Babi Yar, on the edge of Kiev (Ukraine). The Nazis ordered all the Jews in Kiev to assemble on 29 September 1941. In just two days over 33,000 people were marched to a ravine outside the city where they were murdered. Over the following months other groups such as Red Army soldiers, civilians and Roma were massacred here in a similar fashion – it is estimated that around 100,000 people were murdered at this single site.
In some areas, particularly Lithuania and western Ukraine, local nationalist groups assisted with or carried out the shooting of Jewish populations. Historic, widespread antisemitism in these areas was heightened by propaganda which blamed Jewish communists for the Soviet occupation, which Germany had just ‘liberated’ them from.
By the end of 1941, more than one million Jews had been murdered by mobile killing squads. Nearly all of the 200,000 Jews in Lithuania were killed in this way.
SS leaders began to become concerned that the scale of the slaughter their men were carrying out could affect their mental health – so began experimenting with alternative methods of killing. Vans were adapted which pumped their interiors full of carbon monoxide. Killing by gas had been pioneered by the Nazi killing of severely disabled people between 1939 and 1940 and was adapted here for use by the Einsatzgruppen. These gas vans were then used in Chełmno – the first extermination camp, and led to the development of permanent gas chambers in all extermination camps.