On 27 April 1961, Sir Milton Margai led Sierra Leone to independence from Great Britain and became the country's first Prime Minister. Thousands of Sierra Leoneans took to the streets in celebration. The Dominion of Sierra Leone retained a parliamentary system of government and was a member of the Commonwealth of Nations. The leader of the main opposition All People's Congress (APC), Siaka Stevens, along with Isaac Wallace-Johnson, another outspoken critic of the SLPP government, were arrested and placed under house arrest in Freetown, along with sixteen others charged with disrupting the independence celebration.