Born at the chateau of Tonnay-Charente (Charente-Inferieure), France, the daughter of Gabriel de Rochechouart, duc de Mortemart. She was educated at the Convent of St Mary at Saintes, and when she was twenty she became maid-of-honour to Queen Maria Theresa. She married in January 1663 LH de Pardaillan de Gondrin, marquis de Montespan, who was a year younger than herself. By him she had two children, LH Pardaillan de Gondrin, duc d'Antin, born in 1665, and a daughter.
Her brilliant and haughty beauty was only one of the Montespan's charms; she was a cultivated and amusing talker who won the admiration of such competent judges as Saint-Simon and Mme de Sévigné. Nevertheless she was a profound believer in witchcraft, and La Reynie, the chief judge of the court before which the famous poisoning cases were brought, places her first visits to La Voisin in 1665. She received from the sorceress love powders concocted of abominable ingredients for Louis XIV, and in 1666 the "black mass" was said by the priest Etienne Guibourg over her with the usual horrible ceremonial. In 1667 she gained her end, becoming Louis XIV's mistress in July.
Montespan astounded the court by openly resenting his wife's position. He made a scandal by accusing Mme de Montausier of acting as go-between in order to secure the governorship of the dauphin for her husband. He even wore mourning for his wife. Montespan was arrested, but released after a few days' imprisonment. The first of the seven children whom Mme de Montespan bore to the king was born in March 1669, and was entrusted to Mme Scarron, the future Mme de Maintenon, who acted as companion to Mme de Montespan while the king was away at the wars. Her children were legitimatized in 1673 without mention of the mother's name for fear that Montespan might claim them. The eldest, Louis Auguste, became duc de Maine, the second, Louis Cesar, comte de Vexin, and the third, Louise Françoise, demoiselle de Nantes (afterwards duchess of Bourbon).
Meanwhile Montespan had been compelled to retire to Spain, and in 1674 an official separation was declared by the procureur-general Achille de Harlay, assisted by six judges at the Chatelet. When Louis's affections showed signs of cooling, Mme de Montespan had recourse to magic. In 1675 absolution was refused to the king, with the result that his mistress was driven from the court for a short time. It has been thought, that she had conceived the intention of poisoning even as early as 1676, but in 1679. Louis's intrigue with Angélique de Fontanges and her own relegation to the position of superintendent of the queen's household brought matters to a crisis. Mile de Fontanges died a natural death in 1681, though poisoning was suspected.
Meanwhile suspicion was thrown on Mme de Montespan's connexion with La Voisin and her crew by the frequent recurrence of her maid's name, Mlle Desoeillets, in the evidence brought before the Chambre Ardente. From the end of 1680 onwards Louvois, Colbert and Mme de Maintenon all helped to hush up the affair and to prevent further scandal about the mother of the king's legitimatized children. Louis XIV continued to spend some time daily in her apartments, and apparently her brilliance and charm in conversation mitigated to some extent her position of discarded mistress. In 1691 she retired to the Convent of St Joseph with a pension of half a million francs. Her father was governor of Paris, her brother, the duc de Vivonne, a marshal of France, and one of her sisters,
Gabrielle, whose vows were but four years old, became abbess of the wealthy community of Fontevrault. Besides the expenses of her houses and equipage Mme de Montespan spent vast sums on hospitals and charities. She was also a generous patron of letters, and befriended Corneille, Racine and La Fontaine. The last years of her life were given up to penance. When she died at Bourbon 1'Archambault on the 27th of May 1707 the king forbade her children to wear mourning for her. Real regret was felt for her by the duchess of Bourbon and by her younger children--Françoise Marie, Mlle de Blois (1677-1749), married in 1692 to the future regent Orleans, then due de Chartres, and Louis Alexandre, comte de Toulouse (1678-1737).
See P Clement, Madame de Montespan et Louis XIV (Paris, 1869); monographs by Arsène Houssaye (1865) and by H Williams (I903); F Funck-Brentano, Le Drame des poisons (1899); A Durand, "Un Episode du grand regne" in Rev. des questions hist. (Paris, 1868); the contemporary memoirs of Mme de Sevigne, of Saint-Simon, of Bussy-Rabutin and others; also the proceedings of the Chambre Ardente preserved in the Archives de la Bastille (Arsenal Library) and the notes of La Reynie preserved in the Bibliothéque Nationale. She figured in V Sardou's play, L'Affaire des poisons (1907).