The Einsatzgruppen were mobile killing squads. Heinrich Himmler and Reinhard Heydrich formed four small groups of murderers immediately before the Nazi invasion of the Soviet Union. They totaled about 3,000 men.

The Einsatzgruppen entered the Soviet Union behind the army, and murdered, mostly by shooting and gas vans, the undesirables: political "criminals", Polish governmental officials, gypsies and, mostly, Jews.

Jews were rounded up in every village, transported outside to a wooded area or a ravine (natural or constructed by Jews). They (men, women and children) were stripped, shot and buried. Their clothes were sent back to Germany.

Sachar provides a description of one of the most brutal mass exterminations - at a ravine named Babi Yar, near Kiev:

     population was exterminated....

         The riddled bodies were covered with thin layers of earth and the
     under the corpses and seek a hiding place....

         After the main massacre, the site was converted into a more 
     permanent camp to which thousands of victims from other parts of the
     Ukraine could be sent for extermination. It became known as the 
     Syrets camp, taking its name from a nearby Kiev neighborhood. Several hundred
     selected prisoners were quartered there - carpenters, shoemakers,
     tailors, and other artisans - to serve the needs of the SS men and
     replaced by others who continued their duties. In charge of the
     administration and ultimate killing was Paul von Radomski, who seemed
     to crave a reputation for outdoing his sadist colleagues in other

(from Sachar, Abram L. The Redemption of the Unwanted, New York: St. Martin's/Marek, 1983).

Einsatzgruppen were mobile killing squads of the Sicherheitspolizei and Sicherheitsdienst in World War 2. The followed around Nazi forces and killed targets that they were assigned. The Einsatzgruppen were first employed in Austria in March 1938, but their mission and performance there are still a mystery. Seven of the units(approx. 4200 men) followed the German invasion force into German invasion of Poland in September of 1939. They murdered Poland's elite: aristocrat, the intelligentsia, and priest, as well as many Jews while they were rounded up and herded into Jewish Ghettos. Five Units totaling 3,000 men also followed the Wehrmacht(German Army) during its invasion of the USSR in June of 1941 (operation Barbarossa) with orders to kill all Jews as well as Soviet political commissars. By November of 1941 as many as 600,000 Jews had been liquidated. Einsatzgruppen were also used against Soviet partisans, though these operations were often a cloak for helping to implement Hitler's Final Solution. It was planned that six units should be in the United Kingdom following its invasion, codenamed Sealion, which never took place.
