On the 21 June 1941 Nazi forces began the invasion of the Soviet Union. Following in their wake, SS troops sought, in the name of security and in line with Nazi plans for the redistribution of the population of eastern and central Europe, to pacify the newly occupied territories by killing all Jewish men of fighting age. These men were taken from the communities in which they lived, and murdered, often being shot into graves that they had dug themselves. By late August these SS Einsatzgruppen and other itinerant killing squads were murdering Jewish men, women and children. During the autumn, pressure built throughout Nazioccupied Europe for local administrators and governors to deal with their Jewish populations as radically as the murder squads in the east. In December the first of the six death camps constructed on former Polish territory began operation at Chelmno, murdering Jews who had been incarcerated in the ghetto at £odz in specially constructed ‘gas vans’. By the time the leaders of German ministries met with Reinhard Heydrich, the head of the SS security main office, to discuss the ‘Final Solution of the Jewish Question’ in Berlin in January 1942, plans for the construction of three more purpose-built murder facilities had been established. At that meeting, known as the ‘Wannsee Conference’, the principle that the Nazi state would seek to transport Jews from throughout occupied Europe to the east for use in slave labour or to be murdered was disseminated throughout the German ministerial bureaucracy. By late July 1942 Heinrich Himmler had determined that the destination for most deported Jews would be the camp and death facility, Auschwitz-Birkenau, although it would not become the centre of the Nazi extermination campaign until the middle of 1943, when the death camps at Be_zéc, Sobibór and Treblinka began to be dismantled. By that time the majority of the Polish Jewish population had been murdered; the camp at Treblinka alone consumed nearly a million people by the time it closed in autumn 1943. Deportations from throughout Europe to Auschwitz-Birkenau were ongoing, culminating in the spring and summer of 1944 with the frenzied attack on Hungary's Jews.