A poisoning scandal at Versailles implicated aristocrats in witchcraft, black masses, and murder — and reached all the way to the king's own mistress.
The Affair of the Poisons began in 1677 when the death of a cavalry officer revealed letters from his mistress — the Marquise de Brinvilliers — along with vials of untraceable poisons. Under torture, she confessed to poisoning her own father and two brothers to inherit their estates. Her execution opened the door to a far deeper scandal.
Paris police chief Gabriel de la Reynie began investigating and discovered a thriving criminal underground. Fortune tellers, alchemists, and midwives were openly selling 'inheritance powders' — a polite term for poison — to wealthy clients eager to accelerate the deaths of wealthy relatives.
The investigation's most explosive figure was Catherine Deshayes Monvoisin, known as 'La Voisin.' A midwife, fortune teller, and alleged witch with a vast network of aristocratic clients, she was arrested in 1679. Under interrogation, she implicated dozens of France's most prominent noblewomen — and eventually the king's own mistress, Madame de Montespan.
La Voisin claimed Montespan had purchased aphrodisiacs and participated in black masses to maintain Louis XIV's romantic favor. A priest named Guibourg allegedly assisted. Louis, faced with a scandal that could destroy his court's reputation, quietly ordered the investigation shut down in 1682 before it could go further.
The chief investigator noted the bitter irony: 'The enormity of their crimes proved their safeguard.' Thirty-six people were executed — almost all from the lower rungs of Parisian society. Montespan was quietly exiled from court, never tried. De la Reynie, who had documented everything, was not allowed to publish his findings.
One lasting consequence involved Prince Eugene of Savoy. His mother fled France after being implicated in the scandal, and her disgrace barred Eugene from military advancement under Louis XIV. He entered the Habsburg service out of resentment and became one of the greatest generals in European history — dealing serious military blows to the French empire for decades.