Nelson Rolihlahla Mandela was a South African anti-apartheid revolutionary, politician, and philanthropist who served as President of South Africa from 1994 to 1999. He was South Africa's first black chief executive, and the first elected in a fully representative democratic election. His government focused on dismantling the legacy of apartheid through tackling institutionalised racism, poverty and inequality, and fostering racial reconciliation. Politically an African nationalist and democratic socialist, he served as President of the African National Congress from 1991 to 1997. Internationally, Mandela was Secretary General of the Non-Aligned Movement from 1998 to 1999. A Xhosa born to the Thembu royal family, Mandela attended the Fort Hare University and the University of Witwatersrand, where he studied law. Living in Johannesburg, he became involved in anti-colonial politics, joining the ANC and becoming a founding member of its Youth League. After the South African National Party came to power in 1948, he rose to prominence in the ANC's 1952 Defiance Campaign, was appointed superintendent of the organisation's Transvaal chapter and presided over the 1955 Congress of the People. Working as a lawyer, he was repeatedly arrested for seditious activities and, with the ANC leadership, was unsuccessfully prosecuted in the Treason Trial from 1956 to 1961. Influenced by Marxism, he secretly joined the South African Communist Party and sat on its Central Committee. Although initially committed to non-violent protest, in association with the SACP he co-founded the militant Umkhonto we Sizwe in 1961, leading a sabotage campaign against the apartheid government. In 1962, he was arrested, convicted of conspiracy to overthrow the state, and sentenced to life imprisonment in the Rivonia Trial.