On Dec. 10, 1963, Zanzibar achieved independence as a member of the Commonwealth. In January 1964 the Zanzibar government was overthrown by an internal revolution, Sayyid Jamshid ibn Abdullah (who had succeeded to the sultanate in July 1963 on his father's death) was deposed, and a republic was proclaimed.
Although the revolution was carried out by only about 600 armed men under the leadership of the communist-trained "field marshal" John Okello, it won considerable support from the African population. Thousands of Arabs were massacred in riots, and thousands more fled the island. Sheikh Abeid Amani Karume, leader of the Afro-Shirazi Party, was installed as president of the People's Republic of Zanzibar and Pemba. Sheikh Abdulla Kassim Hanga was appointed prime minister, and Abdul Rahman Mohammed ("Babu"), leader of the new left-wing Umma (The Masses) Party (formed by defectors from the ZNP), became minister for defense and external affairs. Pending the establishment of a new constitution, the cabinet and all government departments were placed under the control of a Revolutionary Council of 30 members, which was also vested with temporary legislative powers. Zanzibar was proclaimed a one-party state. Measures taken by the new government included the nationalization of all land, with further powers to confiscate any immovable property without compensation except in cases of undue hardship.