On 26 March 1670, the marquis de Louvois wrote to Saint-Mars to give him some disturbing news. Some weeks earlier, two men had broken into the citadel of Pignerol. One was Nicolas Foucquet’s former valet, La Forêt, the other was the sieur de Valcroissant, who went under the name of Honneste. They were well organised and funded, and their aim was to break Foucquet out of prison. Louvois had frustrated their plan. The valet, La Forêt had been hanged, while Honneste, described as a 'gentleman', was sent to the galleys. Foucquet remained in his chamber.
Now, Louvois, who had placed a spy inside Pignerol, who related to him all that went on, informed Saint-Mars that the two men had been able to make contact with Foucquet’s two valets, Champagne and La Rivière. This was serious enough, but it was now revealed to Saint-Mars that Honneste or one of Foucquet’s valets had managed to speak to 'the prisoner who was brought to you by the major of Dunkirk.'
The prisoner, who had been ordered never to speak to anyone, had refused to say anything. Instead, he told the person on the other side of his door to leave him alone. Louvois suggested that the prisoner probably thought that Saint-Mars had sent someone to test him. ‘You have not taken sufficient precautions to prevent his having any communications with anyone,’ rebuked Louvois; 'and, as it is very important to His Majesty’s service that he has no communication, please inspect carefully inside and outside the place where he is held, and put it in such order that the prisoner cannot see or be seen by anyone, and cannot speak to anyone at all, nor hear those who might want to say anything to him.’
This prisoner would go on to become the Man in the Iron Mask.
