After 27 years in prison, Nelson Mandela was released in 1990. He negotiated for an end of apartheid with President F. W. de Klerk and helped organize the 1994 election where he, Mandela, was elected President. Mainstream press accounts of the time vaguely explain that all of this happened due to "international pressure." Not a lie, but just a small fraction of the truth.
A clue is given by the fact that Mandela's first international trip was to Cuba, where he expressed his admiration and respect for Cuban leader Fidel Castro. Again, the mainstream press did its job by attributing the visit to "Mandela's sympathy for a fellow revolutionary." Not all the truth either. Mandela was expressing his recognition for Cuba's military engagement in Africa, which culminated in the battle of Cuito Cuanavale, the largest battle fought in African territory since WWII. For more than three months in 1987- 88 Cuban forces fought alongside Namibian volunteers against the much vaunted South Africa Defense Force in Angola, driving the South Africans back into Namibia, which was then under occupation. The SADF entered the battle with high confidence but it was soundly defeated by the Cuban forces.
Many South Africans to this day dispute the winner of the battle pointing out (correctly) that the SADF evacuated the battlefield in good order, but a defeat it was, since negotiations (in which Cuba was a part) began shortly after, and what was negotiated were the details of the end of the apartheid regime. True, apartheid would have collapsed anyway under its own weight, but without Cuban intervention it may have even limped into the 21st century.
What about "international pressure"? Yes, there were embargoes by the USA and European countries, but that didn't impede South Africa from arming their military; in fact, at the time of Cuito Cuanavale the SADF was on one the best equipped (and trained) armies in the world. Moreover, when Cuban presence in Angola became substantial, the USA supported the apartheid regime unabashedly, first under Jimmy Carter and his courtier Zbigniew Brzezinski, then even more strongly under Ronald Reagan, the courtier being now Henry Kissinger.
Then there was the Soviet Union. They provided the hardware used by the Cubans including artillery, tanks and planes that matched the SADF armament. They also provided military advisers and trainers. It would then be easy to conclude that the Cubans were just Soviet proxies. Not so; the Cuban leadership and Castro himself were in dissent with their Soviet patrons most of the time, to the intense annoyance of the Soviet leadership, who wanted to avoid a conflict with the USA. They were also in dissent with Soviet advisers in the field, whose expertise in bush wars was not equal to that of Castro and his generals. In fact, Castro followed the battle of Cuito Cuanavale by radio from Havana and personally made many of the tactical decisions.
The final facts are, a tiny country with scarce resources and an ever difficult economic situation took the field in support of an oppressed country in another continent and wrote an important page in history. They did so with great bravery and great professionalism. Help came with no strings attached, something without precedent.
This is a must see documentary about an important but underreported episode of recent history. If your curiosity is whetted you may add to your knowledge with the excellent and balanced account Visions of Freedom: Havana, Washington, Pretoria, and the Struggle for Southern Africa, 1976-1991 (University of North Carolina Press, 2013) by Piero Gleijeses. For a view from the Cuban side see Cuba and Angola: Fighting for Africa's Freedom and Our Own, Pathfinder Press (2013) (various authors including novelist Gabriel García Márquez). The film was available from the rental services until recently, but apparently not any more. You may find it in You Tube.
