President Mandela was elected onto the Students Representative Council at the University College of Fort Hare and in 1940 he was suspended from the College as a result of participating in a student protest.
He worked as mine policeman in Johannesburg in 1940 and he served as Articled clerk with legal firm in 1940. He joined the African National Congress (ANC) in 1942 and he was founder-member of the ANC Youth League (ANCYL) together with Oliver Tambo and Walter Sisulu in 1944.
He served as National Secretary of the the ANCYL in 1948 and he was elected into the National Executive Committee of the ANC in 1949 and became National President of the ANCYL in 1950.
In 1952 president Mandela opened the first African legal partnership with Oliver Tambo in Johannesburg and he was appointed National Volunteer-in-Chief of the Defiance Campaign. During this period he travelled the country organising resistance to discriminatory legislation.
He was arrested in 1952 and charged under the Suppression of Communism Act and given a suspended sentence for his part in the defiance campaign. In the same year he was elected Provincial President of the ANCs Transvaal region and later he was elected as one of the four Deputy Presidents of the ANC by virtue of his being the President of the Transvaal branch.
In 1956 he was among the 156 political activists arrested and charged with high treason; during this time he played legal role in the trial after the original defence lawyers withdrew during the 1960 state of emergency. He was found not guilty on 25 March 1961, after trial of four and a half years.
President Mandela was instrumental in a number of protest actions and campaigns, including the anti-pass law campaigns. He addressed international audiences and travelled widely to gain support for the struggle against apartheid, and to canvass support for Umkhonto WeSizwe. He returned to South Africa in 1962 and was arrested for leaving the country illegally and for incitement to strike.
In 1962 he was convicted and sentenced to five years imprisonment. While serving this sentence, he was charged in the Rivonia trial with sabotage and conspiracy to overthrow the government by revolution. He was sentenced to life imprisonment on 12 June 1964.
All eight of the accused, including Mr Mandela, were sentenced to life imprisonment. He continued to exercise leadership in the education of fellow prisoners and attending to political questions facing the ANC while in Robben Island Prison. In 1982 he was transferred to Pollsmoor Prison and to a house on the grounds of the Victor Verster Prison, near Paarl, in 1988 when it was discovered that he was suffering from tuberculosis.
In 1986 he started holding discussions with SA government representatives on the possibility of negotiation and met with the then State President, PW Botha, at Tuynhuys and the new State President, FW de Klerk in 1989. He was released from prison on 11 February 1990 after the unbanning of the ANC, SACP, PAC and other anti-apartheid organisations. He resumed his leadership role in the ANC, and was appointed Deputy President by the National Executive Committee (NEC) on 2 March 1991.
He undertook a tour of the country, addressing the biggest rallies ever seen in the country's history, and helped re-establish the ANC as legal organisation. In November 1993 he led the ANC in negotiations with the South African Government which culminated in the adoption of the Interim Constitution.
He served as President of the ANC from 1991 to 1997, and led the ANC campaign in the 1994 elections. He was inaugurated as the President of South Africa for a term of five years on 10 May 1994 and served until 14 June 1999. He is Ex-officio member of the ANCs NEC and Ex-officio member of the ANCs National Working Committee since 1998.
He was appointed Mediator in the Burundi Peace Process in 1999.