At the time, the military coup of 1964 was considered a temporary hiccup in Brazil's postwar democracy, but it lasted 21 years and left a very bitter taste. The first period of military rule saw the famous economic miracle, when the economy grew at an astonishing average annual rate of ten percent for a decade, only to come to a juddering halt after 1974, when oil price rises and the increasing burden of debt repayment pushed it off the rails. But most depressing was the effective end of democracy for over a decade, and a time - from 1969 to 1974 - when terror was used against opponents by military hardliners. Brazil, where the desaparecidos numbered a few hundred rather than the tens of thousands butchered in Argentina and Chile, was not the worst military regime on the continent. But it is difficult to overestimate the shock even limited repression caused. It was the first time Brazilians experienced systematic brutality by a government, and even in the years of economic success the military governments were loathed right across the political spectrum.

The coup of 1964 was years in the brewing. It had two root causes: a constitutional crisis and the deepening divides in Brazilian society. In the developed South, relations between trade unions and employers went from bad to worse, as workers struggled to protect their wages against rising inflation. But it was in the Northeast that tension was greatest, as a result of the Peasant Leagues movement. Despite industrial modernization, the rural Northeast was still stuck in a time-warped land tenure system, moulded in the colonial period and in many ways unchanged since then. Peasants, under the charismatic leadership of Francisco Julião and the governor of Pernambuco, Miguel Arrães , began forming co-operatives and occupying estates to press their claim for agrarian reform; the estate owners cried communism and openly agitated for a military coup.

The crisis might still have been avoided by a more skilful president, but Kubitschek's immediate successors were not of his calibre. Quadros resigned after only six months, in August 1961, on the anniversary of Vargas's suicide. He apparently wanted popular reaction to sweep him back into office, but shrunk from suicide and ended up shooting himself in the foot rather than the heart. The masses stayed home, and the vice-president, João Goulart , took over.

Goulart's accession was viewed with horror by the right. He had a reputation as a leftist firebrand, having been a minister of labour under Vargas, and his position was weakened by the fact that he had not succeeded by direct popular vote. As political infighting began to get out of control, with the country polarizing between left and right, Goulart decided to throw himself behind the trade unions and the Peasant Leagues; his nationalist rhetoric rang alarm bells in Washington, and the army began to plot his downfall, with tacit American backing.

The coup, in the tradition of Brazilian coups, was swift and bloodless. On March 31, 1964, troops from Minas Gerais moved on Rio; when the military commanders there refused to oppose them, the game was up for Goulart. After futile efforts to rally resistance in Rio Grande do Sul, he fled into exile in Uruguay, and the first in a long line of generals, Humberto Castelo Branco , became president.