General Olímpio Mourão Filho, a key figure in the Brazilian military, initiated a significant movement of troops towards Rio de Janeiro on the last day of March 1964. His orders came in the context of increasing domestic tensions and fears of a communist threat under President João Goulart, whose administration faced criticism for its leftist policies and alliances. Brazilian military leaders, concerned about the direction of the nation, saw an opportunity to establish control and restore what they perceived as order and stability. With the support of conservative political factions and segments of Brazilian society, Mourão Filho's actions catalyzed the military coup d'état that ultimately led to the overthrow of Goulart. This coup was not only a military takeover but also reflected broader geopolitical dynamics as the United States sought to counter communist influences in Latin America during the Cold War.

Following the successful coup, General Mourão Filho and his allies established a military junta that would govern Brazil for the next 21 years. This period was characterized by authoritarian rule, the suppression of civil liberties, and the persecution of political dissent. The military regime justified its actions by claiming to restore national security and economic stability while stamping out communism. Internationally, the narrative of a preventive strike against communism found favor with military stakeholders and U.S. officials, leading to tacit U.S. support for the new regime.

The consequences of this coup were profound, entrenching military power in Brazilian politics and precipitating significant social, economic, and cultural changes throughout the country. The military dictatorship pursued policies that included economic modernization, but at the cost of human rights, leading to widespread violation of civil liberties and opposition suppression. Historical memory of this period remains contentious in Brazil, with ongoing debates about the legacy of the military regime and its impact on contemporary society.