Biography of Madame Ferron
Madame Ferron was the wife of a Paris lawyer and one of the mistresses of the French king François I. Her jealous husband decided to revenge himself cruelly on the king, and for that purpose visited a brothel, where he contracted syphilis. He then infected his wife who, in her turn, infected the King.
She was the model for Leonardo da Vinci’s (1452–1519) famous portrait La belle Ferronière from 1495, now in the Louvre, and in the 1810 Paris Salon Alexandre Menjaud (1773-1832) presented his picture of François I and "la belle Ferronière"
If you find this story too good to be true, you're quite right. In fact, François’ affair with "la belle Ferronière" is now known to have been a fabrication, dating to some years after the King’s death. The strong moral and dramatic component of the tale, however, secured its survival through the nineteenth century.
The portrait in the Louvre by Leonardo da Vinci was also thought in the nineteenth century to be a portrait of "La Belle Ferronière," but that too has been discounted. Leonardo's picture is probably of Lucrezia Crivelli, one of Ludovico Sforza's mistresses. Ludovico Sforza (1452-1508), a ruthless prince and diplomatist, was a patron of Leonardo da Vinci and other artists.