When Nelson Mandela was released from prison on February 11, 1990, after 27 years of confinement, millions of South Africans didn’t show up to work. Nor did they stay home. They took to the streets in vast numbers, turning every city and town across the country into a gigantic party. Mandela’s freedom was a prelude to their freedom; four years later, the apartheid regime ceded power to a democratically elected government, and Mandela was sworn in as the first legitimate president in the country’s history.

But one South African woman did not leave her home the day Mandela was freed. She locked her door and put a sign up on her gate asking journalists to stay away. Her name was Evelyn Mase. She had once been Nelson Mandela’s wife and had borne four of his children. The couple had divorced 32 years earlier, just three months before Nelson married his second wife, the now famous Winnie Mandela.

Evelyn Mase, Nelson Mandela’s first wife and the mother of four of his children, at her home in Cofimvaba, South Africa, in 1994.

When she did finally speak to the press, what Mase said was shocking. “How can a man who has committed adultery and left his wife and children be Christ?” she asked a journalist. Then she said that Nelson Mandela had serially beaten her and had once tried to strangle her.

Mandela denied the allegation categorically, and the matter rested there, uncomfortably. He was a global hero; scratching around his personal history seemed distasteful.

A quarter of a century later, after Mandela died, it turned out that he had written an affidavit during his divorce proceedings acknowledging that there was violence in his marriage to Mase. The document had sat unread in an archive for 50 years before a historian found it. The story has not aired until now. I write about it at length in my new book, Winnie and Nelson.

“How can a man who has committed adultery and left his wife and children be Christ?”

Couples are notoriously cruel to each other during divorce proceedings, and Mandela’s affidavit is no exception. He paints a picture of Mase as a woman in a paranoid rage. Erroneously convinced that Mandela was having an affair with a fellow political activist, Lilian Ngoyi, Mase conspired to have Ngoyi arrested by the apartheid police, Mandela claimed. His wife was also superstitious, he continued. She paid a diviner a large sum of money to put a potion in Mandela’s food to make him love her again.

Mandela and Winnie, his second wife, in 1958, likely shortly before their wedding.

As for the strangling incident, he said that Mase attacked him with a red-hot poker while he was holding their infant child. He took her by the throat, dragged her to the door, and threw her outside to protect his little daughter from mortal injury.

It was an egregious attack on his wife. Mandela was a well-known philanderer in the 1950s. Whom he was sleeping with was a subject of constant gossip in Johannesburg’s activist ranks. Mase was not paranoid at all. She was just deeply humiliated by her husband’s sex life being the talk of the town.

Nelson Mandela was a global hero; scratching around his personal history seemed distasteful.

So is Nelson Mandela yet another man whose private life condemns him? The story is much more complex than that. I’m fairly certain that we would never have heard of Mandela had he been a good husband and father. He would neither have saved his country from civil war nor overseen the advent of democracy.

Nelson and Winnie Mandela celebrate his release from prison after 27 years behind bars.

This may seem an odd thing to say, but there are at least two reasons why it’s true. For one, his neglect of family and his self-absorption were the flip side of his mastery of the public arena. He lived an astonishingly frenetic life in the 1950s—he was banned, often on the run, a partner in a maniacally busy legal practice, a full-time activist—and he ran his life on adrenaline, and on a lot of extramarital sex.

It was out of the vortex of this obsessive activity that Mandela crafted the series of public personae that made him the pre-eminent Black activist of his age. Early on as the dapper lawyer, then as the underground guerrilla, he made of himself a cult figure embodying the aspirations of Black South Africa. That he was preening and narcissistic and neglectful of the people around him was, I’d argue, a condition of his success.

There is a second connection between Mandela’s poor performance at home and his success on the political stage. He spent a very long time behind bars. And as he grew older in prison, he became the family man he’d never been on the outside. He was filled with remorse. His children’s lives were wrecked, and he firmly believed it to be his fault. While still in jail, he went to astonishing lengths to make amends, largely in vain.

I’m fairly certain that we would never have heard of Mandela had he been a good husband and father.

A connection had finally evolved between his public and private lives. His dual obsessions as an elderly man were to save his family from ruin and his country from civil war; while using his growing influence to try to rescue his damaged children, he also secretly reached out to the apartheid government to make peace. He saw himself as a flawed man whose burden was to spare his family and nation from catastrophe.

Nelson and Winnie Mandela with their daughter Zindziswa and her daughter, following Nelson’s release from prison.

It’s impossible to say for sure, but it seems to me that Mandela the wise peacemaker and Mandela the contrite family man are of a piece. He was singularly attuned to how close his nation was to destruction because his family was too. His political wisdom toward the end of his life was born from deep personal regret.

This is not to say that Mandela’s failings as a husband and a father were redeemed. It’s not like the scales somehow balanced: Mase’s pain versus South Africa’s political settlement. It’s more to say how uncomfortable, how un-fairy-tale-like, life can be. Nelson Mandela became the world’s great peacemaker, not despite being not so nice, but because he was not so nice.

Jonny Steinberg is a South African author. His latest book, Winnie and Nelson: Portrait of a Marriage, is out now from Knopf