Jorge Videla, the former military leader of Argentina, has been sentenced to 50 years for systematically stealing the babies of prisoners.
Videla, 86, was found guilty on Thursday of kidnapping hundreds of babies from leftist activists detained and killed between 1976-1983.
"We have presented evidence showing that the kidnappers plotted to steal the children born to women in captivity," Estela de Carlotto, president of the Grandmothers of Plaza de Mayo, told the AFP news agency.
The rights group has fought in court since 1996, demanding restitution for the children stolen while their mothers were held in clandestine detention.
The group says about 500 children were kidnapped and then raised as their own by families close to the regime.
The case, which Al Jazeera's Teresa Bo, reporting from Buenos Aires, says shocked Argentine society, also included doctors accused of involvement in the kidnappings.
Bo said that the defence's request that Videla be allowed to serve his sentence under house arrest, due to his advanced age, was denied.
It is one of the highest-profile criminal cases to date connected to the so-called dirty war in Argentina.
"It's much more complicated than people realise, and this trial that we're seeing, this conviction today in Buenos Aires, is not the last," said Alex Gibson, a fellow at the Council of Hemispheric Affairs.
"It's been something that the people of Argentina have dealt with since this period of terror."
Videla defended his actions last week, saying in court that the children's mothers were "terrorists".
"All those who gave birth, who I respect as mothers, were active militants in the machinery of terrorism. They used their children as human shields," said the former general, who has already been sentenced to life in prison for crimes against humanity.
Elliott Abrams, a former assistant secretary for human rights at the US department of state, said in January that Washington, an ally of the Videla government, was aware of a systematic practice of stealing children.
"We believed there was a plan, because they were arresting or assassinating a lot of people, and we got the impression that the military government had decided that at least some of the children of those people would be given to other families," he testified from the Argentine consulate in Washington.
"We knew that certain children had been given away while their parents were in prison or deceased. They took them and gave them away."