Marianna Alcoforado (1640 - 1723), was a Portuguese female author, best known for the Letters of a Portuguese Nun.

She was born in Beja, the daughter of a landed proprietor of Alemtejo. Beja was the chief garrison town of the province and the principal theatre of the twenty-eight years' war with Spain that followed the Portuguese revolution of 1640. Marianna's widowed father, occupied with administrative and military commissions, placed her in the wealthy convent of the Conception for security and education. She made her profession as a Franciscan nun at sixteen or earlier, without any real vocation, and lived a routine life in that somewhat relaxed house until her twenty-fifth year, when she met Noel Bouton. This man, afterwards marquis de Chamilly, and marshal of France, was one of the French officers who came to Portugal to serve under the captain, Frederick Schomberg, 1st Duke of Schomberg, the re-organizer of the Portuguese army.

During the years 1665-1667 Chamilly spent much of his time in and about Beja, and probably became acquainted with the Alcoforado family through Marianna's brother, who was a soldier. Custom permitted those in religious orders to receive and entertain visitors, and Chamilly found it easy to get round the trustful nun. Before long their affair became known and caused a scandal, and Chamilly deserted Marianna and returned to France. This resulted in Marianna writing the letters that made her famous.

There are signs in the fifth letter that Marianna had begun to conquer her passion, and after a life of rigid penance, accompanied by much suffering, she died at the age of eighty-three. The letters came into the possession of the comte de Guilleragues, director of the Gazette de France, who turned them into French, and they were published anonymously in Paris in January 1669. A Cologne edition of the same year stated that Chamilly was their addressee, which is confirmed by St Simon and Duclos, but the name of their authoress remained undivulged. In 1810, however, Jean François Boissonade de Fontarabie discovered Marianna's name written in a copy of the first edition by a contemporary hand, and the veracity of this ascription has been placed beyond doubt by the investigations of Luciano Cordeiro, who found a tradition in Beja connecting the French captain and the Portuguese nun.

The letters created a sensation on their first appearance, running through five editions in a year, and, to exploit their popularity, second parts, replies and new replies were issued from the press in quick succession. Notwithstanding that the Portuguese original of the five letters is lost, their genuineness is as patent as the spuriousness of their followers, and though Jean-Jacques Rousseau was ready to wager they were written by a man, the principal critics of Portugal and France have decided against him. It is now generally recognized that the letters are a verbatim translation from the Portuguese.

Reference

• This entry incorporates public domain text originally from the 1911 Encyclopaedia Britannica.