Sir Samuel Lewis (1843–1903) was a member of the Legislative Council for more than 20 years and the first mayor of Freetown. Sir Milton Augustus Strieby Margai (1895–1964), the grandson of a Mende warrior chief, was the founder of the SLPP and the first prime minister of Sierra Leone, a post he held until his death. Sir Albert Michael Margai (1910–80) succeeded his half-brother as prime minister from 1964 to 1967. Siaka Probyn Stevens (1905–88), the founder of the APC, was prime minister from 1968 to 1971 and became the republic's first president from 1971 to 1985. John Musselman Karefa-Smart (b. 1915) served as minister of lands, mines, and labor, in which capacity he organized Sierra Leone's diamond industry, and also served as assistant director-general of WHO from 1965 to 1970. Davidson Nicol (1924–94) was his country's permanent representative to the UN from 1969 to 1971, served as president of the Security Council in 1970, and became executive director of UNITAR in 1972. Foday Sankoh (b. 1937) is the leader of the Revolutionary United Front, a guerrilla group that terrorized villages in the early 1990s.