03/04/2018 12:48 AM AEST | Updated 03/04/2018 5:17 AM AEST

Winnie Madikizela-Mandela, Anti-Apartheid Campaigner, Is Dead At 81

Winnie Madikizela-Mandela, the anti-apartheid campaigner and controversial wife of former South African President Nelson Mandela while he was imprisoned on Robben Island, died on Monday. She was 81.

A family spokesman confirmed Madikizela-Mandela’s death to Reuters, saying she had been in and out of the hospital with a long illness since the start of the year.

“She fought valiantly against the apartheid state and sacrificed her life for the freedom of the country,” the spokesman said in a statement. “She kept the memory of her imprisoned husband Nelson Mandela alive during his years on Robben Island and helped give the struggle for justice in South Africa one its most recognizable faces.”

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Winnie Madikizela-Mandela, an anti-apartheid campaigner and wife of former South African President Nelson Mandela, is seen in Johannesburg in December 2017.

Madikizela-Mandela was known as a tireless activist who spent decades standing up against racial segregation and discrimination imposed by the South African government from 1948 to 1994.

Born in 1936, Nomzamo Winifred Zanyiwe Madikizela was part of a large family in Transkei, South Africa. She turned down a scholarship to the United States and reportedly became the first black woman in South Africa to serve as a social worker.

She was in her early 20s in 1958 when she married Nelson Mandela, who would go on to become the country’s first black president.

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South African anti-apartheid activist and politician Nelson Mandela is seen with wife Winnie Madikizela-Mandela in the early '90s.

After Mandela was sentenced to life behind bars for treason in 1964, Madikizela-Mandela became known for carrying on his activism. Her work, which earned her the nickname “Mother of the Nation,” led to her own years-long detention, arrest, torture, and banishment by white authorities.

She later wrote, according to The New York Times, that that experience was “what changed me, what brutalized me so much that I knew what it is to hate.”

After her husband’s release from prison in 1990, the couple took increasingly divergent approaches to their political work.

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Winnie Madikizela-Mandela is seen during her exile in Brandfort, South Africa, in 1977.

Madikizela-Mandela came to be seen as a polarizing figure and faced various criminal convictions, including in a case that involved the 1988 kidnapping of four youths as part of a plot to discredit a local minister. Madikizela-Mandela maintained that she was unaware the young men had been assaulted at her home, but a judge concluded the abductions must have been carried out with her approval.

She was sentenced in 1991 to six years in jail for her role in the case, which involved the murder of a 14-year-old boy. Upon appeal, her sentence was reduced to a fine.

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Madikizela-Mandela, seen in early 2017, was memorialized on Monday as a leader and a survivor of “the most brutal period of state terror in apartheid South Africa.”

In 1993, she separated from Nelson Mandela, who was elected president of South Africa the following year. She was fired from his Cabinet following allegations of corruption not long after. They divorced in 1996.

In later years, Madikizela-Mandela both defended and apologized for her actions. “I am not sorry. I will never be sorry,” she told the London Evening Standard in 2010. “I would do everything I did again if I had to. Everything.”

The Nelson Mandela Foundation mourned her death Monday in a statement that recognized her as a leader and a survivor of “the most brutal period of state terror in apartheid South Africa.”

“All South Africans are indebted to Mama Winnie, whether they acknowledge it or not,” Professor Njabulo Ndebele, the foundation’s chairman, said. “From the witness of her life, we knew we could stand tall; we knew also we could falter and stumble. Either condition was an affirmation of life. Her cry was our cry, and in 2018 we can say we did triumph.”