On  September 5, 1661, by order of Louis XIV, Nicolas Fouquet, France’s finance minister, was arrested at Nantes by d’Artagnan, commander of the King’s Musketeers, assisted by one of his men holding the cavalry rank of sergeant, Bénigne de Saint-Mars. Eventually convicted for embezzlement, Fouquet was sent in 1664 to the prison of Pignerol (present-day Pinerolo) in Piedmont, of which the newly appointed governor was the same Saint-Mars. In 1669, an unnamed prisoner was brought to Pignerol from Dunkirk. He was joined by the disgraced Comte de Lauzun in 1671 and, in 1679, by an Italian diplomat, the double-dealing Comte Mattioli. Meanwhile the unidentified prisoner served as a valet to Fouquet, who died in 1680. The following year, when Saint-Mars was moved to the prison at Exiles, also in Piedmont, the prisoners, minus Lauzun who had regained royal favour, went with him. In 1687 Saint-Mars was reassigned to the…

Source: TLSOn the trail of the Man in the Iron Mask – David Coward