After the German invasion of Poland in World War II and the division of Poland between Germany and the Soviet Union, many yeshivas (Jewish schools of Torah study, generally for boys and men) that had previously been part of Poland found themselves under Soviet communist rule, which did not tolerate religious institutions. The yeshivas therefore escaped to Vilnius in Lithuania on the advice of Rabbi Chaim Ozer Grodzinski. In Lithuania, the yeshivas were able to function fully for over a year and many of the students survived the Holocaust because of their taking refuge there, either because they managed to escape from there or because they were ultimately deported to other areas of Russia that the Nazis did not reach. Many students, however, did not manage to escape and were killed by the Nazis or their Lithuanian collaborators. Background Before the Second World War, there were many yeshivas in Eastern Europe, mostly in what is present-day Belarus and Lithuania as well as Poland, and what was then mostly the Second Polish Republic. These include the yeshivas of Mir, Slabodka, Telshe, Radin, Lomza, Kaminetz, Kletsk, Grodno, Baranovich, and Bialystok. Thousands of students flocked to Eastern Europe from all over the world, mostly from local locations, but also from Sweden, the United States, Germany, England, Belgium, and more, to study in the famous yeshivas under venerable rosh yeshivas. Escape to Vilnius At the outbreak of World War II in September 1939, the Nazis overran Poland before partitioning it with the Soviet Union. Rabbi Chaim Ozer Grodzinski, a leader of European Torah Jewry, then sent out an urgent message to all the yeshivas that had just fallen under Soviet rule, instructing them to escape to Vilnius (), previously part of Poland which at that point had also fallen under Soviet rule. However, Grodzinski knew that the Russians and Lithuanians had made an agreement that they would return Vilnius to Lithuania, which had been their capital city for centuries. Many of the yeshivas, including Mir, Kletsk, Kaminetz, Baranovich, Grodno, and Radin, therefore escaped to Vilnius. Altogether, there were about 25,000 Jewish refugees in Vilnius at the time. In an interview published by Rabbi Dov Eliach, a student recalled that the Polish refugees were warmly welcomed by the Jews of Vilnius, with many of them hosting refugees in their homes, sometimes even aiding their guests financially. Although the Prime Minister of Lithuania treated the Jews