Mandela was put in jail for his involvement in preparations for mass terrorism that was to target both white and black civilians and for collaborating with the Soviets and other Easter Bloc countries.
He wasn't put in jail for his views.
International groups such as Amnesty International were at the trial and admitted it was fair. The government claimed that unlike the Communist countries Mandela was defending, that their judiciary was at least independent from the government.
They could have executed him if it were not so.
He was offered release from prison several times as long as he renounced violence. He declined and preferred to stay in prison as martyr.
He also approved the brutal method of killing on black 'traitors' (anyone who disagreed with their group) called necklacing: putting a tire around someone, spraying them with petrol and burning them to a slow death.
While in prison he also approved the bombing and killing of civilians and civilian areas and targets. He admitted to this in his book.
He approved that 90% of the ANC's bombings should be on civilians and only 10% on state buildings and infrastructure.
He also wrote a manuscript called 'How to be a good Communist' which proposed cutting off traitors noses.
He had visited Cuba, East Germany and the Soviet Union and had received training in these countries.
When he was released in 1990 he once again did not renounce violence but called on it to be stepped up which lead to thousands of deaths and a massive crime-wave till the promised elections in 1994.
Today about the same amount of South Africans die every year as in the Syria right now.
Since 1990 80 000 whites have been killed including over 3000 farmers.
Its also mot mentioned in the media but in 1992 a national referendum was held were whites voted YES to continue the negotiations and have multi-racial elections in 1994. If they voted NO, Apartheid would not have ended.
The reason whites didn't want to hand over power to a black government was that they knew the country would become a hell-hole ruled by an alliance of Communists and ex-terrorists. Look at the rest of Africa???
The government is massively corrupt and are trying their best to end freedom of speech.
Under Apartheid they used to fund their operations via the drug trade and car theft which spread to several African countries. Today they are still working these people.
Their rule brought in a massive crime-wave especially since Mandela kept pardoning thousands of criminals on special occasions and letting them on the streets.
Far more people are dying now than under Apartheid, unemployment is more than double and black people are even poorer. The exception being the elites and the well connected who benefit from the racial quotas and race laws which bar whites from much of the workplace 22 years after Apartheid has ended.