THE REICH POPULATION RESETTLEMENT OFFICE-Reichskommissariat für die Festigung Deutschen Volkstums (RKfDV).
The Nazi Party (NSDAP) had big plans for expansion of German sovereign territory in Eastern Europe. They called it 'Lebensraum' (Living Space).
In order to accomplish these plans it needed to occupy or re-occupy not only the lands it held prior to WW1, but lost as a result of the carve-up afterwards. In that instance, people of German origin were not forced to leave, but of course had to become citizens of the new 'foregn' authorities which they hated. These Germans were called "Volksdeutsch" by the Nazis. In 1937 when these plans were drawn up, Hitler was agitating for these people to once again be citizens of a 'Greater Germany'.
This plan included a shift of the local populations from Poland and European Russia (Estonia, Latvia and Lithuania).
The Office of Resettlement called VoMi, abbreviated from 'Volksdeutsche Mittelstelle', a party controlled office originally intended to look after the welfare of ethnic Germans (Volksdeutsche), was headed by Werner Lorenz and was located in Berlin. His first task was to draw up plans for the expansion of the Reich when the day came.
When war finally came in September 1939, Poland was the first country to be occupied. A month later, the Nazis then called the Resettlement Office or VoMi office the RKfDV Hauptamt. In 1941 Hitler would hand control of this office to Himmler. Between September 1939 and mid 1942, hundreds of thousands of Jews and Poles had been killed or moved further east, the Jews to the 'Death Camps' of Sobibor, Chelnmo, Treblinka and Belzec, and the Poles to a new 'Government General' area set up in Poland and controlled by Governor Hans Frank.
The houses, farms and businesses, bank accounts vacated by these people were appropriated by VoMi and over half a million ethnic Germans settled in their place.
Wherever the SS were located in Eastern Europe there was a VoMi office which worked closely with both the RSHA and the WVHA.
Many officers of this organisation were charged with war crimes after WW2.