In 1942, the first trainload of Jews in Holland were sent to concentration camps. A few years earlier, tens of thousands of Jews had fled from Germany to Holland, which maintained an open-door immigration policy. But soon after, the Nazis occupied Holland and proceeded to make it Judenrein (clean of Jews). Perhaps the most famous Dutch Jew was Anne Frank, a teenage girl whose diary has become the most widely-read account of life during the Holocaust. In 2005, Holland's prime minister apologized for his country's collaboration with the Nazis.