It's weird, let me tell you.
There were some small feminist movements in Brazil in the mid 19th century. In 1891, during a rewrite of the constitution, they had enough support to petition the government for an explicit right to vote. The government refused to make an explicit declaration but also removed all specific references to men. In effect, this changed nothing. Officials would generally not register women or permit them to vote. And this was not some mass conservative resistance on their part. The government never punished them or ordered them to do otherwise. It was just understood that the gender-neutral language, in effect, meant men. In fact, one judge declared that gender-neutral language meant only men could vote since the language did not explicitly say women could vote.
It's important to emphasize how little hold feminism and suffragettes had in Brazil. This was not the government resisting popular will. It was the government ignoring a tiny percentage of women. Even American suffragette Carrie Chatt thought there was no zeal for suffrage in most of the women of Brazil. Brazilian feminism was an extremely elite and bourgeois movement. The estimates of support for suffrage in Brazil vary but never go above 10%. They usually settle around 3%. However, they were a very elite group of women. They were likely to be well educated, have extensive foreign ties, and be from good and wealthy families. They lived in cities and usually had husbands engaged in relatively high prestige professions if they were married. A disproportionate number of them worked, but usually in upper class jobs. They were usually highly educated and were virtually all literate. Their leader, for example, was a scientist who contributed extensively to the understanding of (among other things) Amphibians.
They created a fairly conservative feminist movement. They emphasized women's domestic role and shunned revolutionary rhetoric or alliances with more radical groups. They often condemned wider calls for wider women's liberation and effectively made a movement that was unthreatening to Brazilian elites. For a few radicals this was a conscious strategy, but largely it reflected the demographics of who feminists were. This worked and the cause quickly became popular among Brazilian elites but didn't filter down very far. It entirely failed to reach the roughly 85% of the population that was rural, poor farmers. It didn't do very well among the urban poor either. It was somewhat more successful in the middle class, but that was a small group. It looked on track to win at some point: it had no loud voice to demand suffrage but it had little opposition from the powerful.
And then Brazil suffered a... sort of fascist coup in 1930. The election of 1930 was extremely corrupt and marred by violence, including the assassination of one of the vice-presidential candidates. After the Liberal Alliance candidate, Getulio Dornelles Vargas, was defeated, the army revolted and installed him as president. He created a dictatorship founded on largely fascist principles, openly praising Mussolini and espousing corporatism. But the Liberal Alliance didn't want a dictatorship of any sort. They pushed him to create a constitution in 1932. In the midst of this, he declared that women would henceforth have the right to vote as a political maneuver. He was attempting to curry elite support. To a lesser extent, it was part of a program of modernization and industrialization. This was a relatively minor part of a larger package, but that is the beginning of female suffrage in Brazil.
Vargas eventually managed to crush dissent but this meant his own party fell apart. Rather than trying to form or join another political party, he simply declared himself an independent. He then issued a constitution in 1934 which did keep most of his promises, like giving women the vote, but also gave him more power. Despite this, turnout was low because voting was compulsory for men but not for women. The women who remained in the feminist movement began to win office and tried to push for greater rights for women. But since they had defined themselves very narrowly and largely not engaged with ideas of general women's liberation or allied with more radical movements, they had trouble coalescing around a new objective. Some joined other movements. Many just went back to their lives. Vargas, meanwhile, started banning political parties and disempowering the legislature, taking away the power they had just gained. (It must be said, this probably had little to do with feminism. In fact, Vargas encouraged women to enter the workforce. But he was, you know, a dictator who didn't like other politicians having power.)
Vargas continued to consolidate power and feminists were not really a strong part of the opposition. But the US, which had always been mildly opposed to Vargas's anti-democratic and pro-fascist sensibilities, increased pressure on the regime in the late '30s and '40s. This was partly because of World War 2 and partly because after 1937 Vargas was looking more and more undeniably like a fascist dictator. The US encouraged Vargas to moderate his policies and pressured him to join the war. This included some support for feminist organizations, especially from wealthier and more powerful American organizations. Vargas did indeed join the war and Brazil contributed fairly significantly to the war effort. This led to increased women in the workforce on a small scale, but as above that had already been the trend. But the new rhetoric of anti-fascism was, unsurprisingly, immediately seized on by the opposition to condemn the Vargas regime. The US quietly encouraged Brazil to transition away from fascism. Vargas responded by making concessions, promising freedom after the war was over.
As the war drew to a close, the military effectively told Vargas to resign or suffer a coup. Vargas chose to resign. He was permitted to retire (and even re-entered politics later). Brazil became a democracy again and in the new elections, women were required to vote too. This was probably done because Vargas thought women would tend to vote for his favored party. This finally brought women into electoral parity with men, even if society as a whole remained deeply patriarchal and feminism remained weak and popular mostly with a subsection of elites. Still, that subsection began to push on women's rights and has had some victories. But Brazilian women remain relatively politically inactive. Brazil has one of the lowest percentages of female politicians in Latin America. Feminist political organizations remain small and not especially influential.
In short, Brazilian women's suffrage was the result of a fascist dictator currying elite support.
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