Midway through David James Smith’s absorbing account of the pre-Robben Island life of Nelson Mandela, the author breaks from his narrative to recount a scene in a hospital room in Johannesburg. In December 2004, Makgatho, Mandela’s estranged son from his first marriage, was dying of AIDS following years of alcoholism and aimlessness. In his last days, other members of Mandela’s family, including Ndileka—the daughter of Mandela’s elder son, who had died in a car crash in July 1969—and Mandela’s daughter Maki arranged a meeting between the two men. What followed, as described by Smith, was an awkward, painful encounter. At one point, Maki guided Mandela’s hand over his dying son’s to encourage a moment of physical intimacy—only to have Mandela yank his hand away. “He was frozen. He just could not accept his own feelings,” Ndileka recalled to Smith. Makgatho, she said, “landed in that hospital bed because of my grandfather.”

Ndileka’s words resound with hurt and bitterness, with what seems like a willful desire to tarnish the legacy of her near-deified grandfather. Yet they also have, alas, the ring of authenticity. The Mandela who emerges from Smith’s complex portrait—pieced together from diaries, oral histories, and dozens of interviews with his family and surviving members of the ANC inner circle around Mandela—combines greatness with pettiness, compassion with coldness, altruism with selfishness. Smith shows again and again that Mandela’s deepening commitment to the anti-apartheid struggle damaged those closest to him, and, in the end, led him to accept almost casually the role of martyr, despite the terrible consequences for nearly everyone in his orbit.

Much of Mandela’s life—his early family history and schooldays in Transkei, his move to Johannesburg, his years as an attorney in the increasingly repressive and racist apartheid state, and his ascendance to the upper echelons of the the African National Congress—has been recounted in detail by Mandela himself in Long Walk to Freedom, the autobiography that he co-wrote with Richard Stengel. And, indeed, Smith relies on this resource to fill up the first third or so of his narrative. But the tale begins to take off, and to venture into incompletely charted territory, in Smith’s account of Mandela’s deepening political commitment. The memories of ANC activists such as Ruth Mompati, Fatima Meer, and Ahmed Kathrada vividly recreate the clandestine excitement, the exhilarating multiracialism, and the physical risks of anti-apartheid activism in the 1950s and early 1960s.

Smith does a fine job explaining the rivalry with the Pan-Africanist Congress, which opposed the multiracial makeup of the ANC, and of conveying Mandela’s force of personality—and dandyism—that awed nearly everyone he met. The story of Mandela’s rise within the party ranks parallels the tale of his messy personal life, especially the breakup of his marriage to his first wife, Evelyn Mase, which left her deeply resentful. “With hindsight, it rather looks as if he outgrew Evelyn as he soared professional and politically, ascending to the peak of his young powers just as their marriage fell apart.” There is also fresh information on the courtship between Mandela and Winnie Madikizela, the naïve, beautiful country girl from Pondoland who became swept up in the struggle.

The massacre of dozens of black protesters in Sharpeville in 1960 pushed the ANC’s young turks, including Mandela, Walter Sisulu, and Mandela’s former law partner Oliver Tambo, to abandon the doctrine of non-violence that had characterized the ANC since its founding in 1912. The following year, they created the ANC’s armed wing, Umkhonto Wa Sezwe, and Mandela—despite an utter lack of knowledge of the tactics of guerrilla warfare and sabotage—became its commander.