During 1933–1948, the British government limited Jewish immigration to Palestine with quotas, and following the rise of Nazism to power in Germany, illegal immigration to Palestine commenced. The illegal immigration was known as Aliyah Bet ("secondary immigration"), or Ha'apalah, and was organized by the Mossad Le'aliyah Bet, as well as by the Irgun. Immigration was done mainly by sea, and to a lesser extent overland through Iraq and Syria.