Ha'apala

Aliyah Bet (Hebrew: 'עלייה ב‎, "Aliyah 'B'" – bet being the second letter of the Hebrew alphabet) was the code name given to illegal immigration by Jews to Mandatory Palestine in violation of British White Paper of 1939 restrictions, in the years 1934 to 1948. In modern-day Israel it has also been called by the Hebrew term Ha'pala (Hebrew: הַעְפָּלָה‎; ascension). The Aliyah Bet is distinguished from the Aliyah Aleph ("Aliyah 'A'", Aleph being the first letter of the Hebrew alphabet): the limited Jewish immigration permitted by British authorities in the same period.

During Ha'pala, several Jewish organizations worked together to facilitate immigration beyond the established quotas. As persecution of Jews intensified in Europe during the Nazi era, the urgency driving the immigration also became more acute. Those who participated in the immigration efforts consistently refused to term it "illegal", instead calling it "clandestine."

Ha'pala occurred in two phases. First, from 1934 to 1942, it was an effort to enable European Jews to escape Nazi persecution and murder. From 1945 to 1948, in a stage known as Bricha, it was an effort to find homes for Jewish survivors of the Nazi crimes (Sh'erit ha-Pletah) who were among the millions of displaced persons ("DPs") languishing in refugee camps in occupied Germany. During the first phase, several organizations (including Revisionists) led the effort; after World War II, the Mossad LeAliyah Bet ("the Institute for Aliyah B"), an arm of the Haganah, took charge.

...
Wikipedia