Cornio Smit, 8, was killed in the December 23, 1985 blast at a shopping centre in Amanzimtoti near Durban.
"I thought my son was a hero... He died for the freedom of people who were under pressure," his father Johan Smit told the first day of the Truth and Reconciliation Commission's Johannesburg hearings.
Without the ANC's bombing campaign, Smit said, few white people would have found out about the struggle.
He said he had met the parents of the man who planted the bomb and had no grudge against them. "I was happy to tell them I had no hatred in my heart."
President Nelson Mandela made a surprise visit to the commission's hearings on Monday, and stayed to hear testimony about alleged torture in one of the ANC's Angolan camps.
Mandela heard George Dube tell how he was beaten and made to do hard labour for three years in the ANC's Kibashe "rehabilitation centre".
"We were not given water to wash. We were beaten almost every day. We had swollen eyes and mouths. I was also beaten on the soles of my feet with electrical cord."
Dube, who asked the commission to help him become a chef, was placed in protective custody after his testimony at his own request, commission deputy chairman Dr Alex Boraine said.
Mandela said he could not comment on Dube's claims as the matter was sub-judice.
The president also said he had no doubt about the commission's success to date.
"Until we know what crimes were committed against innocent people, there will never be reconciliation in the proper sense of the word. To forgive and forget means you must know what really happened," Mandela said.
A survivor of a 1983 ANC bomb blast which killed 19 people in Pretoria said he wanted the masterminds of the blast brought to justice.
The blast blew James Simpson's spectacles from his face and ripped his watch off his arm. Shards of glass were lodged in his eyes and his face was cut and bloodied.
Also on Monday, the commission heard about a 1993 attack on a taxi in which eight eight people were killed in Tembisa on the East Rand. Madrina Jokazi said her husband Bulelwa Sigudu and Wiseman Mashwabana, both ANC members, died in the attack.
A five-year-old girl who survived the attack later said she had seen police attack the taxi, Jokazi said. "I was told police and Zulu people were involved," she said.
The commission was asked to probe the parcel-bomb murder of exiled black consciousness activist Onkgopotse Tiro in Botswana in February 1974. His mother Moleseng appealed for help to bring her son's body home for a proper burial.
Sarah Mthembu told the commission security forces shot dead her son in Johannesburg's Alexandra township during a violent uprising in 1986 and then admitted they had killed the wrong person.
Police, she said, had wanted to kill her student activist daughter Maria, but instead shot son Jerry, 16.
Mthembu said she could forgive the police for their past actions, except for the person who killed her son.
Her daughter Maria said she had a baby while in detention and was forced to keep the infant in cold cells for 11 days.
The commission heard testimony about seven deaths in detention within months of each other in 1969. Nicodimus Kgoathe died in police custody in February 1969 after allegedly slipping on a bar of soap while bathing.
A month later, fellow detainee James Lenkoe also died, with police claiming he had hanged himself with his belt.
Kgoathe's son Ben said an inquest magistrate had found nobody was to blame for his father's death despite a district surgeon testifying that he had found evidence that Kgoathe was whipped and beaten.
An independent post-mortem found Lenkoe had been tortured, the commission heard.
A small group of women demonstrated with posters outside Monday's hearings with an appeal to perpetrators of human rights abuses to confess.
The African National Congress Women's League members displayed posters asking who had plotted a massacre at Sebokeng in 1993, and what had happened to Stanza Bopape, an activist who disappeared in police custody in 1988.
"Tell us where our loved ones are buried," read a poster. "Anyone who knows, please come forward," read another.
The commission's hearings next week move to KwaZulu-Natal, the heartland of the Inkatha Freedom Party which opposes the commission. Tutu ruled out a postponement of the Durban hearings but conceded that no IFP members had come forward to testify.