The formal end of the apartheid government in South Africa was hard-won. It took decades of activism from both inside and outside the country, as well as international economic pressure, to end the regime that allowed the country’s white minority to subjugate its Black majority. This work culminated in the dismantling of apartheid between 1990 and 1994. On April 27, 1994, the country elected Nelson Mandela, an activist who had spent 27 years in prison for his opposition to apartheid, in its first free presidential election.

The white minority who controlled the apartheid government were Afrikaners—descendants of mostly Dutch colonists who had invaded South Africa starting in the 17th century. Although Afrikaner oppression of Black South Africans predates the formal establishment of apartheid in 1948, apartheid legalized and enforced a specific racial ideology that separated South Africans into legally distinct racial groups: white, African, “coloured” (i.e., multiracial) and Indian. The apartheid government used violence to enforce segregation between these groups, and forcibly separated many families containing people assigned to different racial categories.

Black South Africans resisted apartheid from the very beginning. In the early 1950s, the African National Congress, or ANC, launched a Defiance Campaign. The purpose of this campaign was for Black South Africans to break apartheid laws by entering white areas, using white facilities and refusing to carry “passes”—domestic passports the government used to restrict the movements of Black South Africans in their own country. In response, the government banned the ANC in 1960, and arrested the prominent ANC activist Nelson Mandela in August 1962.

The banning of the ANC and the incarceration of its leaders forced many ANC members into exile. But it did not stop resistance within South Africa, says Wessel Visser, a history lecturer at Stellenbosch University in South Africa.

“What many dissidents started to do inside the country was to form a kind of an alternative…resistance movement called the United Democratic Front,” he says. The UDF, formed in 1983, “was a [collaboration] of church leaders and political leaders who were not banned at that stage, community leaders, trade unionists, etc.,” he says.

Archbishop Desmond Tutu and Reverend Allan Boesak, two of the UDF’s main leaders, “started to organize marches to parliament, in Cape Town, in Pretoria, Johannesburg—crowds of 50 to 80,000 people, so there was definitely a groundswell of resistance against apartheid,” he says. And around the world, this activism drew attention.

One of the big moments for international awareness of apartheid was in 1976, when thousands of Black children in the Soweto township protested a government policy mandating that all classes be taught in Afrikaans. Police responded to the protests with violence, killing at least 176 people and injuring over 1,000 more. The massacre drew more attention to activists’ calls to divest from South Africa, something the United Nations General Assembly had first called on member states to do back in 1962.

Campaigns for economic sanctions against South Africa gained steam in the 1980s, but faced considerable resistance from two important heads of state: United States President Ronald Reagan and United Kingdom Prime Minister Margaret Thatcher. Both Reagan and Thatcher condemned Mandela and the ANC as communists and terrorists at a time when the apartheid government promoted itself as a Cold War ally against communism.

Reagan vetoed the Comprehensive Anti-Apartheid Act of 1986, but the U.S. Congress overrode his decision with a two-thirds majority, passing the act to impose sanctions on South Africa. The U.K. also imposed limited sanctions despite Thatcher’s objections. The combination of international sanctions placed significant economic pressure on South Africa, which was then at war with the present-day nations of Namibia, Zambia and Angola.

Anti-apartheid activism also drew international attention to Mandela. International advocates urged South Africa to release him and other imprisoned ANC members and allow exiled members back into the country.

“As early as 1984 there were attempts by national intelligence inside the government structures and also by some of the ministers to make contact with the ANC … and sound out the waters of a possibility of a negotiated settlement,” says Anton Ehlers, a history lecturer at Stellenbosch University.

Visser speculates that the fall of the Berlin Wall in November 1989 helped speed the process of ending apartheid along because it took away one of the government’s main defenses of itself among Western allies: that it needed to remain in place to fight communism. “The argument that the ANC are only the puppets of the Reds couldn’t be used anymore,” Visser says, both because the Cold War was ending and because the ANC now had a lot more support in Europe and the U.S.

Mandela finally walked free on February 11, 1990, and negotiations to end apartheid formally began that year. These negotiations lasted for four years, ending with the election of Mandela as president. In 1996, the country initiated a Truth and Reconciliation Commission in an attempt to reckon with the gross human rights violations during apartheid.