Obituary: Albertina Sisulu, political activist

Albertina Sisulu, who has died at her Johannesburg home, was much loved in South Africa for her courage, humility and integrity during the struggle by the African National Congress against apartheid rule. Her death at the age of 92 leaves only Nelson Mandela, 93, and Ahmed Kathrada, 82, from the ANC "old guard" who were at the forefront during the early campaigns for one man-one vote from the 1940s to the 1960s.

Mandela, Kathrada and Mrs Sisulu's late husband Walter, who died in her arms eight years ago, were together jailed for life on charges of sabotage amounting to treason in 1964. They served more than a quarter of a century in prison on Robben Island.

While her husband was imprisoned, Mrs Sisulu, known affectionately as "Ma", was in and out of jail. She was subjected to a banning order for five years, preventing her from meeting more than two people at a time and from being quoted in the press, and then placed under house arrest for another ten. In Walter's absence and through all her own difficulties, she managed to bring up seven children, two of them adopted. "All those years I never had, you know, a comfortable life," she commented years later. "I got used to prison, banning and detention. I did not mind going to jail myself and I had to learn to cope without Walter. But when my children went to jail, I felt that the oppressors were breaking me at the knees."

Nobel Peace Prize laureate Archbishop Desmond Tutu commented: "Try as they might they could not break her spirit, they could not make her bitter, they could not defeat her love."

Walter was Nelson Mandela's best friend and closest comrade. Ma Sisulu, who trained as a nurse, introduced Mandela to her own friend and fellow nurse Evelyn Mase, who married Mandela and bore him four children. The marriage collapsed amidst deep acrimony, and Mandela subsequently married a young township beauty, Nomzamo Winfreda Madikizela.

Ma Sisulu's relationship with Winnie Mandela was turbulent, coming near to open warfare, and was at its most tragic and awful when a hit squad from Winnie's vigilante bodyguard, the notorious Mandela United Football Club, shot dead Abu-Baker Asvat, a township doctor for whom Albertina worked as a nurse and receptionist. Asvat had examined 14-year-old Stompie Moeketsi, beaten up by Winnie, and warned her that the child would die if not taken to hospital. Dr Asvat was killed in front of Ma Sisulu and Stompie's body was later found in a mortuary. Recalling holding the dying doctor in a pool of his own blood, Ma Sisulu said: "Dr Asvat was my child. Losing him was like losing my own child. But then he was also a father to me (in the years Walter was imprisoned).He was also the person I went to when I was in trouble."

She was born Notsikelelo Albertina Thethiwe to a peasant couple, Bonilizwe and Monikazi, in rural Transkei. Notsikelelo chose her "Christian" name from a list presented to her when she arrived at her mission school, where she became a Catholic. Orphaned at an early age, she abandoned her ambitions to train either as a teacher or nun and instead left home for Johannesburg, 600 miles to the north, to train as nurse and midwife at the city's hospital for "non-Europeans", a career choice which importantly enabled her to earn a wage as she studied and trained. She met Walter, from a nearby mud village in Transkei but fathered by an Irish railway worker he barely knew, and they married in 1944.

Theirs, unusually within the liberation struggle, was a deeply tender relationship. "We loved each other very much," she once said. "We were like two chickens. One always walking behind the other."

Walter Sisulu became secretary-general of the ANC in 1949. Decades later, he said he was only able to accept the responsibility because Albertina, whom he described as "remarkable", made it possible. Selfless and steadfast, she was the rock he could rely upon. "I was not paid a salary," he said. "I wasn't going to earn anything. I depended on my wife. I say remarkable, because with no means she was able to keep the family together."

At the same time Albertina joined the ANC Women's League, fiercely organised against the Bantu Education Act, which among other restrictions banned the teaching of mathematics to black people, and helped lead the historic 9 August 1956 march by thousands of women of all races to parliament in Pretoria to protest against the extension of the Pass Laws to women. The slogan of the 1956 march was, "You strike a woman, you strike a rock."

In late 1958 Ma Sisulu and Winnie Mandela were imprisoned together for defying the Pass Laws, which required black people to carry identity documents when in whites-only areas. It was the first time that Winnie, then only 24 and pregnant with her first child by Nelson, had been arrested. She started to bleed, but Ma Sisulu managed to avert the threatened miscarriage of the young wife of her husband's best friend.

The episode should have bonded two women who had so much in common, but thereafter they grew apart. When Ma Sisulu was appointed co-president in 1984 of the United Democratic Front, a proxy for the banned and exiled ANC, Winnie was furious, refused to have anything to do with the new group and formed the Mandela United Football Club, which ran amok in Soweto.

Gradually Albertina Sisulu came to be known as the "Mother of the Nation", a crown once reserved for Winnie Mandela in the pre-Football Club years.

In 1994, with the advent of democracy in South Africa, Ma Sisulu was given the honour of nominating Nelson Mandela for election by parliament as the first black president of South Africa.She served one term as a backbench MP before retiring.

Mrs Sisulu had been watching TV at her home in Johannesburg on Thursday night when she had a coughing fit and slumped in her chair. Paramedics were called but could not revive her.

She had lived to see her children take prominent positions in post-apartheid South Africa. A daughter, Lindiwe, is defence minister, and a son, Max, is speaker of parliament.

She is survived by five other children and numerous grandchildren.