24 April 1970
Gambia is one of the smallest countries in West Africa. It gained its independence from Britain on 18 February 1965. On 24 April 1970 Gambia became a republic within the Commonwealth of Nations. In 2013 Gambian President Yahya Jammeh withdrew his country from the Commonwealth, reportedly because of grievances with western countries lecturing African countries on human rights and democracy.
References

Freeman, C., (2013), Gambia to leave the Commonwealth after president accuses West of lecturing him on human rights, from The Telegraph, 03 October [online], Available at www.telegraph.co.uk [Accessed: 24 March 2014]|Access Gambia, Gambia history Page, from Access Gambia, [online], Available at www.accessgambia.com [Accessed: 24 March 2014]