In late 1938, due to domestic Arab pressure in Palestine relating to local objections to Zionist immigration waves, the British government announced in (what became known as) the 1939 White Paper that it was to reduce Jewish migration to Palestine, and at that point the main body of Zionism decided to cease conforming with British regulations.
When World War II broke out, the Mossad LeAliyah Bet became virtually paralyzed and its activities were only renewed in August 1945.
Since that time and until the founding of Israel, the Mossad LeAliyah Bet was able to bring an additional 64 ships with over 70,000 Jewish immigrants (many of whom were Holocaust survivors).
In addition to the sea, although on a much smaller scale, the Mossad LeAliyah Bet also brought immigrants via land, from the Arab world.
With the founding of Israel, Mossad LeAliyah Bet served as a basis for the agency Lishkat Hakesher (Liaison Bureau), codenamed Nativ (נתיב "Path"), created in 1953 and also headed by Meirov, which brought Jews from Soviet bloc, the Arab world, and other countries.