Aliya Beth was a term used for illegal immigration to British Mandate of Palestine. Legal immigration was termed Aliya Aleph. The main reason that the British wanted to relenquish their mandate for Palestine was the continuing flow of Jewish refugees to Palestine, even sending back the Passengers of the "Exodus 1947" to Germany didn't stop the ships. Over 100,000 people sailed over the years to Israel. Many were interned in Mauritius and Cyprus for years, over 1600 drowned at sea a few thousands managed to enter Israel.

Two periods of the Aliya Beth, 1934-42 and 1945-48. In the first period the refugees were fleeing from Nazi held countries, many forced to leave they had no place to go because of the Closed Door policies of the democracies, also Palestine was closed by the White Letter policy of the British Government. In the scond period it was survivors of the Holocaust that filled the ships strugling to reach Israel in spite of the British Mandate government. The Mossad a unit of the Haganah was responsible for all the boats in the second period, in the first period the Revionists and private organizations also sailed ships. In all there were 142 sailings, made on 120 ships. Over 107,000 passengers sailed on Aliya beth ships.

Four major disasters happened, The Hagannah blew a hole in the "Patria" a deport ship taking the detainees to Mauritius (November 1940), 200 lost. The "Salvador" sunk December 1940 near Istanbul, 260 drowned about 100 saved later boarded the Darien II [1], "Struma" February 1942 torpedod by the Russians 770 lost, and the "Mafkura" torpedoed by the Germans August 1944, 400 lost.