He rose to power as dictator after toppling the president Arturo Illia in a coup d'état self-named "Argentine Revolution".

[5] When the Armed Forces replaced the radical president in government with General Juan Carlos Onganía, they interrupted an attempt to set up the republic and led the country to the violence of the 1970s and subsequent decline.

However, he demonstrated a disregard for civil authority when he initially refused to call off his troops after a ceasefire agreement had been approved by President José María Guido and his cabinet, and was only convinced to follow orders after a tense meeting.

[10] As military dictator, Onganía suspended political parties and supported a policy of Participacionismo (Participationism, supported by the trade unionist José Alonso and then by the general secretary of the CGT-Azopardo, Augusto Vandor), by which representatives of various interest groups such as industry, labor, and agriculture, would form committees to advise the government.

Onganía also suspended the right to strike (Law 16,936) and supported a corporatist economic and social policy, enforced particularly in Cordoba by the appointed governor, Carlos Caballero.

[13] Onganía also ordered repression on all forms of "immoralism", proscribing miniskirts, long hair for boys, and all avant-garde artistic movements.

Ongania's government was weakened by a popular uprising of workers and students that took place in the whole of the country, in particular in the interior, in cities such as Córdoba in 1969 (known as "El Cordobazo") or Rosario (the Rosariazo).