Leading to World War II, nearly all Jewish businesses in Nazi Germany had either collapsed under financial pressure and declining profits, or had been forced to sell out to the Nazi German government as part of the "Aryanization" policy inaugurated in 1937. As the war started, of Jews took place originally as part of Operation Tannenberg against the Polish nation. The much larger and methodical mass killings of Jews began with the onset of Operation Barbarossa in 1941. Led by "Einsatzgruppen" and the Order Police battalions, the destruction of European Jews took place with the active participation of local Auxiliary Police including Belarusian, Estonian, Latvian, Lithuanian, and Ukrainian units.