The last word in the Bible is ve'ya'al - a call (made by the King of Persia) to the Jews in the Diaspora to make 'aliya' - a return from the Diaspora to live in the Land of Israel. Ha'apala is a modern Hebrew word (with a root from the Bible as well) that refers to the epic enterprise of Aliya Bet - the organized clandestine immigration of Jews to the Land of Israel during the British Mandate of Palestine. The immigrants who participated in Aliya Bet are called ma'apilim in Hebrew.

Aliya Bet was the result of severe restrictions that the British imposed on immigration of Jews to Palestine. The restrictions had started back in 1922, but became brutal (especially in light of the desperate situation in Europe on the eve of WW-II) with the publication of the White Paper of 1939, which restricted Jewish immigration to mere 10,000 immigrants per year (this quota was later revised up slightly to 1,500 per month). The British authorities allocated immigration certificates according to the quota they set, forcing tens of thousands of Jews to try and arrive illegally, i.e. without the necessary certificates.

Aliya Bet started in 1934 following the rise of the Nazi regime, continued even during the difficult period of WW-II, and concluded in May 1948 when Israel became an independent state. The organization in charge of Aliya Bet on behalf of the Jewish Agency was HaMossad LeAliyah Bet, established in 1939 and headed by Shaul Avigur (Meirov) who reported directly to Ben-Gurion. Aliya Bet was conducted in two ways: by sea, from ports and shores in Southern/Eastern Europe and North-African, and by land, through the northern border.

Between 1934 and the beginning of WW-II, about 15,000 ma'apilim arrived on board 43 vessels. Two additional vessels were turned away by the British, and two sunk. The vessels came close to the shores and the ma'apilim were taken quickly ashore to escape capture. During WW-II additional 15,000 ma'apilim arrived on board 21 vessels. The ma'apilim, who came from the Balkan countries, first arrived in Turkish ports and from there by land to Palestine (during the war Britain allowed Jews in Turkey to enter Palestine legally). Five more vessels sunk, resulting in 1,583 casualties.

The "Golden Age" of Aliya Bet was its post WW-II stage, during the three years between the end of WW-II in Europe in mid 1945 and the declaration of Israel as an independent state on May 14, 1948. During this stage, over 70,000 ma'apilim took part in 66 voyages, including the most famous voyage by far of the ship Exodus 1947. There were no major disasters (only two ships sunk, 8 ma'apilim drowned in one of them), in contrast to the several horrifying disasters of the previous stages. Ten ma'apilim died as a result of clashes with the British forces.

The British reaction to Aliya Bet after WW-II was an impressive, and effective, blockade by their Navy of the Palestinian coast. Only 12 Aliya Bet vessels managed to run this blockade, with just 2,108 ma'apilim on board. The rest of the ma'apilim - 66,170 people (this number excludes 1,014 who were allowed to enter legally following the famous "La Spazia Affair" and 1,136 who arrived after May 14, 1948) - were caught and detained by the British. The vast majority of them was detained in special detention camps in Cyprus. Other detention places included the Atlit detention camp south of Haifa, and 2 camps near Hamburg, Germany where the Exodus' ma'apilim were detained. The British gradually released the ma'apilim as part of their allocated monthly quota of certificates (1,500 per month).

Aliya Bet after WW-II had a huge impact: it brought the sympathy and support of the world public opinion to the Zionist cause, and demonstrated the resolve of the Jewish people to pursue independence. Thus, it was a major factor (with many historians thinking THE factor) in leading the United Nations to pass its historic resolution of the 29th of November 1947, which paved the way to the establishment of the State of Israel. A good source of information about Aliya Bet is the website www.palyam.org.

The stamp was issued in 1964 to commemorate 30 years to the beginning of organized Aliya Bet. It was designed by M. & G. Shamir. Another stamp commemorating Aliya Bet was issued in 1997.