He was arrested in 1962 and sentenced to five years' hard labor for leaving the country illegally and inciting blacks to strike.
A year later, police uncovered the ANC's underground headquarters on a farm near Johannesburg and seized documents outlining plans for a guerrilla campaign. At a time when African colonies were one by one becoming independent states, Mandela and seven co-defendants were sentenced to life in prison.
"I do not deny that I planned sabotage," he told the court. "I did not plan it in a spirit of recklessness, nor because I have any love of violence. I planned it as a result of a calm and sober assessment of the political situation that had arisen after years of tyranny, exploitation and oppression of my people by whites."
The ANC's armed wing was later involved in a series of high-profile bombings that killed civilians, and many in the white minority viewed the imprisoned Mandela as a terrorist. Up until 2008, when President George W. Bush rescinded the order, he could not visit the U.S. without a waiver from the secretary of state certifying he was not a terrorist.
From the late 1960s South Africa gradually became an international pariah, expelled from the U.N., banned from the Olympics. In 1973 Mandela refused a government offer of release on condition he agree to confine himself to his native Transkei. In 1982 he and other top ANC inmates were moved off Robben Island to a mainland prison. Three years later Mandela was again offered freedom, and again he refused unless segregation laws were scrapped and the government negotiated with the ANC.
In 1989, F.W. de Klerk became president. This Afrikaner recognized the end was near for white-ruled South Africa. Mandela, for his part, continued, even in his last weeks in prison, to advocate nationalizing banks, mines and monopoly industries — a stance that frightened the white business community.