Maria Teresa Horta, a Portuguese feminist writer who helped shatter her conservative country’s strictures on women, died on Feb. 4 at her home in Lisbon. She was 87.

Her death was announced on Facebook by her publisher, Dom Quixote. The Portuguese prime minister, Luis Montenegro, paid tribute to her on X, calling her “an important example of freedom and the struggle to recognize the place of women.”

Ms. Horta was the last surviving member of the celebrated writers known as the “Three Marias,” who together wrote the landmark 1972 book “Novas Cartas Portuguesas” (“New Portuguese Letters”). A collection of letters the women wrote to one another about their problems as women in Portugal, it opened up a world of repressed female sexuality, infuriated the country’s ham-fisted dictatorship and led to their arrest and criminal prosecution on charges of indecency and abuse of freedom of the press.

“To feminists around the world, as well as to champions of a free press, the police action against the Portuguese women in June 1972 was an outrage that slowly became the focus of an international protest movement,” Time magazine wrote in July 1973.

The Three Marias — Ms. Horta, Maria Isabel Barreno (1939-2016) and Maria Velho da Costa (1938-2020) — became international feminist folk heroes, and the book’s fame alerted the world to repression under the Portuguese dictatorship. Simone de Beauvoir, Marguerite Duras and Adrienne Rich were among the writers who declared their public support. The National Organization for Women voted to make the case its first international feminist cause.