Despite the indifference of most Europeans and the collaboration of others in the murder of Jews during the Holocaust, individuals in every European country and from all religious backgrounds risked their lives to help Jews. Rescue efforts ranged from the isolated actions of individuals to organized networks both small and large. In autumn 1943, the resistance movement in German-occupied Denmark organized a rescue operation, in which fishermen clandestinely ferried some 7,200 Jews (of the country's total Jewish population of 7,800) in small fishing boats, to safety in neutral Sweden. In occupied Poland, from the beginning of the deportation of Jews from the Warsaw ghetto to the Treblinka killing center in late July 1942 until the German occupiers leveled the city in the autumn of 1944, as many as 20,000 Jews were living in hiding in Warsaw and its environs with the help of Polish civilians. Some European churches, orphanages, and families provided hiding places for Jews, and in some cases, individuals aided Jews already in hiding (such as Anne Frank and her family in the Netherlands). In France, the Protestant population of the small village of Le Chambon-sur-Lignon sheltered several thousand refugees, most of them Jews.
A number of individuals also used their personal influence to rescue Jews. In Budapest, Swedish diplomat Raoul Wallenberg , Swiss diplomat Carl Lutz, and Italian citizen Giorgio Perlasca (posing as a Spanish diplomat), provided tens of thousands of Jews with certifications exempting the bearers from most anti-Jewish measures decreed by the German-allied Hungarian government. In Bulgaria in 1943, an open protest by key political, intellectual, and religious figures induced King Boris III to reverse the decision of his government to comply with the German request to deport Jews living within the country's formal borders. From his base in London, Jan Karski, a courier for the Polish government-in-exile, sought to expose Nazi plans to murder the Jews. Karski gave reports of mass killings to Allied leaders, including President Franklin D. Roosevelt, with whom he met in July 1943. Some US-based groups engaged in rescue efforts. The Quakers' American Friends Service Committee, the Unitarians, and other groups coordinated relief activities for Jewish refugees in France, Portugal, and Spain. A variety of other American groups (both religious and secular, Jewish and non-Jewish) cooperated in securing entry visas into the United States and arranging placement and, in some cases, eventual repatriation for around 1,000 unaccompanied Jewish refugee children between 1934 and 1942.