Sisulu was - with Nelson Mandela and Oliver Tambo (obituary, April 26 1993) - the third of the triumvirate whose steady commitment to the cause of non-racialism contributed more than any other individual's to the realisation of democracy in South Africa. The closest of friends, their contributions were each subtly different, supplementing each other in a way which was perhaps crucial to the outcome of the struggle: Mandela, the dignified leader who led above all by example; Tambo, who took on the burden of the exile years, and the small and slightly dishevelled figure of Sisulu.
He will no doubt always be remembered as "Nelson's aide". It is the way most journalists refer to him and a position he held formally - as deputy president of the African National Congress - until his belated retirement from office on December 17 1994, just eight months after the election of the new democratic government, under the presidency of Nelson Mandela.
The extent to which he was more than a mere aide is a matter for surmise, but there is evidence that his influence was huge. On a mid-1990s visit to Robben Island - their shared home for more than a quarter of a century - Mandela recalled how, in late 1984, he took the crucial decision to open negotiations with the National Party government, asking for permission to see the senior ANC officials incarcerated with him. "I calculated that if I convinced Walter Sisulu, he would help convince the rest," Mandela explained, in tribute to the standing of the aide who had once been his mentor.
It was in 1941 that Sisulu, then the regional leader of the ANC in Johannesburg, and living in Soweto, took in the young lodger with whose name history will always link him. Soon afterwards, Sisulu persuaded Mandela to join the ANC. But, crucial though the two men were to each other and the liberation movement, Sisulu's personal story of political struggle started before that.
Born two years before the outbreak of the first world war he was - despite his mixed parentage and pale complexion - raised in the tribal tradition by an uncle, a minor chief, undergoing Xhosa initiation rites. Educated at a local Anglican missionary school, he was forced to find work at the age of 15, initially at a Johannesburg dairy, to support the family after his uncle's death. He worked at a series of jobs, including the inevitable stint in a Johannesburg gold mine, as well as a period in domestic service, bringing his mother and sister with him to Johannesburg in the early 1930s.
In 1940, he was fired from a bakery where he was working for organising a national strike. In the same year, now a fiery young militant nursing strong antipathy towards whites, he joined the ANC. In 1944, he, Mandela and Tambo formed the ANC Youth League. Sisulu swiftly rose through the ranks of the ANC to the position of secretary general in 1949.
It was in the 1940s that he was first jailed, after getting involved in an altercation with a white ticket collector who had confiscated a black child's season ticket. It was also in this period that he met his wife, Albertina; theirs was one of the most durable and celebrated marriages of the struggle, the couple marking their 50th wedding anniversary at a party presided over by Mandela in July 1994.
Though he was a key figure in the leadership of the "defiance campaign" from 1952, Sisulu's experience working with anti-apartheid leaders of other races - notably Indian activists - and a subsequent five-month tour of eastern bloc countries, Israel and Britain appear to have ameliorated his fervent black nationalism. Supporting the launch of the multiracial Congress alliance in 1954, he was soon seen as an opponent by the "Africanist" group in the ANC.
During the early years of confrontation with the white Nationalist government, Sisulu was repeatedly banned, jailed and placed under house arrest before going underground in 1963 to join the armed struggle under Mandela's command. Captured four months later, in the July 11 raid on the ANC's secret HQ at Lilliesleaf Farm, Rivonia, he was sentenced to life imprisonment with Mandela and others accused in the famous Rivonia trial.
Sisulu was released from Robben Island in late 1989 with other senior members of the ANC, in a trial run for Mandela's release the following year. Already in his late 70s and suffering from a heart problem, he nevertheless found himself catapulted back to the forefront of the anti-apartheid struggle, as "internal" leader of the ANC. With Mandela's eventual release, his leadership years appeared to be over.
But he was pressed into service once again in July 1991, when he was drafted as deputy president to forestall a Mandela succession battle which was threatening to break out among the next generation of ANC leaders. Excused service in the government of national unity, after the ANC's election victory in April 1994, he was finally allowed to stand down in favour of the man who was to go on to become the successor to Mandela as president, Thabo Mbeki, that December. He retired to the same small Soweto house where his mother had taken in washing more than 60 years before.
Shortly after his release from Robben Island, Sisulu told an American interviewer that he did not know whether he would live to see the end of apartheid. He did, of course, live to see the realisation of that dream to which he had contributed so much. And time may show that it was not his only contribution to the future of South Africa.
He is survived by Albertina and eight children. The white foreman may not have realised it when he entered into his liaison with a black peasant girl in 1911, but he could well have founded something of a political dynasty.
· Walter Max Ulyate Sisulu, freedom fighter, born May 18 1912; died May 5 2003
Mary Benson writes:
During the ceremony in which Nelson Mandela was inaugurated president of South Africa on ay 10 1994, an almost private incident occurred: as he concluded his speech, a greatly moved Walter Sisulu reached out to take his hand. Fifty years before, Sisulu, Oliver Tambo and Mandela had led the Youth League, 30 years earlier they had been imprisoned on Robben Island. Surely unique were this trio of friends who never deviated in their loyalty to each other and to the cause.
Mandela, a born leader of commanding presence, became the most renowned, while Tambo, the quiet diplomat, won international support for the ANC. But it was the calm, wise Sisulu in the background whom many came to regard as the outstanding thinker and organiser.
In 1952, when I first interviewed him, it struck me that his early experiences as a miner, as a kitchen boy and a factory worker, meant that he, more than any other leader, knew just what it meant to be regarded by whites as a "native". Dogged, and determined to educate himself, he had studied English grammar and picked up ideas about trade unionism; fascinated by Xhosa history and culture, he had written about tribal heroes for the publication Bantu World.
We met in the ANC's dilapidated office in Johannesburg. As the organisation's first paid secretary-general, he earned five pounds a month and was in the thick of planning the defiance campaign - the significance of his role is seldom noted, just as his contribution as main witness for the defence in the Rivonia trial has been passed over.
Joel Joffe, attorney for the defence, recalls Sisulu's "brilliance" in withstanding the prosecutor's prolonged attack. As soon as he had taken the measure of Dr Yutar, it was as if he forgot he was in the witness box. Banned from public platforms for 11 years, now he dominated the situation. Only once was his cool confidence shaken: when Yutar declared that the police did not arrest indiscriminately, an incensed Sisulu retorted that people were arrested for no offence.
"How do you know?" Yutar asked.
"I know!" And Sisulu told of his wife Albertina, held in 90-day detention, of the arrest of his 15-year-old son Lungi, and of his own recent experiences: "In 1962, I was arrested six times. I know the position in this country."
Yutar's sarcastic, "You know?" stung him to retaliate: "I wish you were in the position of an African!"
Fellow prisoners on Robben Island found Sisulu a warm, understanding father figure. During those years he had to live with the knowledge of the torture of his daughter Lindiwe and of the repeated imprisonment of Albertina, then of his son Zwelakhe.
· The writer and anti-apartheid activist Mary Benson died in 2000.