The first postcolonial Sierra Leone government was headed by Dr. Milton Augustus Strieby Margai from April 27, 1961, until his death on April 28, 1964. Dr. Margai was the chief architect of Sierra Leone's independence from Britain. He was born on December 7, 1895, in Moyamba District and received his early education at the Evangelical United Brethren (EUB) church school in Bonthe District and at the Albert Academy in Freetown. Dr. Margai was the first person from the Protectorate (the area outside of the colony later renamed the Provinces) to graduate from FBC in 1921, where he earned a bachelor of arts degree, and was also the first from the Protectorate to qualify as a medical doctor. He studied medicine at King's College, Durham University and graduated in 1926. Before he entered active politics, Dr. Margai set up private practice in the Protectorate after twenty-two years as a medical officer in the British colonial service. Until his retirement as a senior medical officer in 1950, Dr. Margai served in the colony (this area became Freetown and with its environs is referred to as the Western Area) and the Protectorate, where he taught midwifery to indigenous women, contributed to improving health care and hygiene, and boosted adult literacy.

Dr. Margai first entered politics at the local level in the 1930s because he opposed the political marginalization of the Protectorate peoples. He first represented Bonthe as a nonchief member in the Protectorate assembly. By 1950 he was working toward a fair representation of the Provinces in the legislative assembly and had become the head of the politically oriented Sierra Leone Organization Society (SOS) to promote agricultural cooperation. His colleagues in the SOS included Dr. John A. M. Karefa-Smart, whose maternal pedigree was Fula; Sir Albert, Kandeh Bureh, Stevens, and Dr. William H. Fitzjohn. In 1951 Dr. Margai, alongside others like Alhaji Dr. Muhammad Sanusi (M. S.) Mustapha, helped found the SLPP, which was a merger of the Protectorate Educational Progressive Union (PEPU), the SOS, and the People's Party (PP) founded by the Reverend E. N. Jones (Lamina Sankoh). Dr. Margai provided strong leadership for PEPU in the 1940s after its founding by mainly Protectorate chiefs and others to promote education as a priority in the Protectorate. By 1954 Dr. Margai was chief minister, and in 1958, under a new preindependence constitution, he was named premier.