President Tabare Vazquez proclaimed June 19 a day to oppose the political violence and human rights abuses that have afflicted the nation since the 1960s.
"Never Again" Day adds a theme of political reconciliation to the existing June 19 national holiday celebrating the birthday of Uruguayan independence hero Jose Artigas.
Vazquez gathered old enemies and survivors of violence for the ceremony in which he placed a wreath at a downtown monument to Artigas as hundred of people cheered and waved Uruguay's light blue-and-white flag.
Vazquez, a socialist, embraced Pedro Bordaberry, the son of the man who imposed a repressive, military-backed dictatorship in the 1970s.
Former President Juan Maria Bordaberry was ousted by the military in 1976, but the right-wing officers remained in control until 1985. Bordaberry is currently in prison, facing charges in connection with 14 dissidents killed during his regime, including a senator whose son attended Wednesday's ceremony.
Also on hand were a founder of the leftist Tupamaro guerrillas that carried out many violent attacks and killings in the 1960s. So was Vazquez's brother Jorge, who was imprisoned for his activities as a member of the Popular Revolutionary Organization, another guerrilla band.
Some groups, including an organization of the dictatorship's victims, criticized Vazquez's initiative, saying it equated the violence of the military dictatorship with that of those who opposed it.