Following the German invasion and occupation of Poland in September 1939,
Heinrich Himmler embarked on a program, known as
Heim ins Reich (approximate translation:
Return to the Nation) which involved driving out the native population in areas of Poland and replacing them with ethnic Germans (
Volksdeutsche) from various countries, such as the
Baltic states and Soviet-occupied eastern Poland. On 13 October 1939 Himmler appointed Sandberger the chief of the Northeast Central Immigration Office (
Einwandererzentralstelle Nord-Ost) and tasked with the "racial evaluation" (
rassische Bewertung) of the various
Volksdeutsche immigrants. Sandberger also performed this task in western Prussia, deporting Jews from Schneidemühl (today,
Piła) to
Lublin to enable Baltic Germans to be settled there. In May 1940, he was transferred to
Alsace after the
fall of France to perform the same function. In April 1941, Himmler assigned him to coordinate the removal of
Slovenes from northern
Slovenia following the German defeat of
Yugoslavia. In June 1941, Sandberger was appointed chief of
Sonderkommando 1a of
Einsatzgruppe A. During the first two weeks of
the German invasion of the Soviet Union, which began on 22 June 1941, Sandberger traveled with
Franz Walter Stahlecker, the commander of Einsatzgruppe A. Sandberger was involved since March 1941 in the distribution of a business plan for the
RSHA and a director of the curriculum organization of the schools (
Lehrplangestaltung der Schulen). == Knowledge of the Führer Order ==