Following the invasion of Poland in 1939 most of the 3.5 million Polish Jews were rounded up and confined to newly established ghettos by Nazi Germany. The system was intended to isolate the Jews from the outside world in order to facilitate their exploitation and abuse. The supply of food was inadequate, living conditions were cramped and unsanitary, and the Jews had no way to earn money. Malnutrition and lack of medicine led to soaring mortality rates. In 1941, the initial victories of the Wehrmacht over the Soviet Union inspired plans for the German colonisation of occupied Poland, including all territory within the new district of General Government. At the Wannsee Conference held near Berlin on 20 January 1942, new plans were outlined for the genocide of the Jews, known as the "Final Solution" to the Jewish Question. The extermination programme was codenamed Operation Reinhard. and was separate from the "Einsatzgruppen" mass killing operations in Eastern Europe, in which half a million Jews had already been murdered.