The earliest document about this prisoner is a letter of 19 July 1669 from Louvois, secretary of state for war, written from Saint-Germain, the King's residence outside Paris, to Bénigne d'Auvergne de Saint-Mars, the captain who had guarded Fouquet at Pignerol since 1665.
Le Roy m'ayant comandé de faire conduire à Pignerol le nommé Eustache d'Auger, il est de la dernière importance à son service qu'il soit gardé avec une grande seureté, et qu'il ne puisse donner de ses nouvelles en nulle manière, ni par lettres à qui que ce soit. Je vous en donne advis par advance, afin que vous puissiez faire accomoder un cachot où vous le mettrez seurement, observant de faire en sorte que les jours qu'aura le lieu où il sera, ne donnent point sur des lieux qui puissent estre abordez de personne, et qu'il y ayt assez de portes fermées, les unes sur les autres, pour que vos sentinelles ne puissent rien entendre. Il faudra que vous portiez vous mesme à ce misérable, une fois le jour, de quoy vivre toute la journée, et que vous n'escoutiez jamais, soubs quelque prétexte que ce puisse estre, ce qu'il voudra vous dire, le menaçant tousjours de le faire mourir s'il vous ouvre jamais la bouche pour vous parler d'autre chose que de ses nécessités. […] vous ferez préparer les meubles qui sont nécessaires pour la vie de celui que l'on vous amènera, observant que, comme ce n'est qu'un valet, il ne luy en faut pas de bien considérables.
"The King having commanded me to have the man named Eustache d'Auger conducted to Pignerol, it is of the last importance to his service that he be guarded with great security and that he be unable to give news of himself in any manner, nor by letter to anyone. I give you notice in advance so that you can have a dungeon fitted where you will put him securely, taking care that the windows of the place give on to no spot that anyone can approach, and that there are enough doors closing one on another that your sentries can hear nothing. You must yourself carry to this wretch, once a day, enough to live on for the whole day, and never listen, under any pretext whatever, to what he may want to tell you, threatening him always with death if he ever opens his mouth to speak to you of anything but his needs. […] as he is only a valet, he does not need very considerable [furniture]."
What it fixes. The letter fixes a named prisoner, a dungeon designed so that he could neither be seen from outside nor heard by the sentries, food carried by the captain himself, a death threat against speech, and the social rank of a valet. What it does not contain. It contains no mask, no reason, no master, no place of arrest and no word about his face.
Nine days later the King signed three orders, to Captain de Vauroy, sergeant-major of Dunkirk, to the marquis de Piennes, governor of Pignerol, and to Saint-Mars. The war-office minutes of all three leave the name blank ("le nommé ….", Iung 1873, pp. 187–188; vol. 234, fols 271, 272 and 274 per Laloy). The order to Vauroy gives the only stated ground: "estant mal satisfait de la conduite du nommé …., et voulant m'assurer de sa personne", "being ill satisfied with the conduct of the man named …., and wishing to make sure of his person". Vauroy was to seize him, conduct him himself to Pignerol, and come back to report. Saint-Mars acknowledged delivery in a letter the editions date 21 August: "M. de Vauroy a remis entre mes mains le nommé Eustache d'Auger", adding that he told the man in Vauroy's presence that if he spoke to him or anyone of anything but his needs "je lui mettrois mon épée dans le ventre" (Roux-Fazillac 1801, pièces; Laloy, p. 104). Louvois's reply of 10 September acknowledges letters "des 24 et dernier du mois passé", so the delivery fell between 20 and 24 August.
The same reply allows the prisoner a prayer book, mass on Sundays and feast days "without being in the same place" as Fouquet's chaplain, and confession "three or four times a year if he wishes it, and no more" (Delort 1829, I, p. 157). On 25 September the prisoner "sent to you last" is unwell and may be bled without waiting for orders (I, p. 158). On 17 December, after Fouquet's valet Champagne was caught passing letters, Louvois orders half-circle grilles and close hurdles on the windows of "the one who has just arrived" so that he can see nothing but the sky, "to avoid similar accidents" (I, pp. 159–161). On 26 March 1670 Louvois has heard that a man called Honneste or one of Fouquet's valets spoke to "the prisoner brought to you by the major of Dunkirk" and asked whether he had nothing of consequence to say, and the prisoner answered that they should leave him in peace; Saint-Mars is to inspect the cell and make it so that the prisoner "ne puisse voir ni estre veu de personne, et ne puisse parler à qui que ce soit" (I, pp. 167–168). Saint-Mars, 12 April 1670: curious people ask news of "mon prisonnier" and why so many retrenchments, and he tells them "des contes jaunes", tall tales (I, p. 169).
Three points in this first year bear on the identification. The name is written out on the two originals (19 July and 21 August) and blank on the three minutes, which is why every editor from Roux-Fazillac onward has read the name differently: d'Auger (Roux-Fazillac, Delort, Laloy), Dauger (Iung, Lair's transcription, Mongrédien, Sonnino), Danger (Lair's judgement, Petitfils, and the handwriting analysis that Bernard Caire, who examined the original letters, presented in 1987), and d'Angers in the original of 8 April 1680, which is legible in Jean-Marc Dabos's photograph. The place of arrest is nowhere stated; "Dunkirk" is an inference from Vauroy's post, and "Calais" rests on a reimbursement order for Vauroy's journey that the archivist Stanislas Brugnon found among the papers of Colbert, the King's finance minister (Bibliothèque nationale, Mélanges Colbert, vol. 282, fol. 276 v°), and produced at a conference on the Iron Mask held at Cannes in 1987: 3,000 livres (a state prisoner's keep at Pignerol was set at four livres a day) "pour avoir été lui quatrième de ladite ville de Dunkerque en celle de Calais, et de ladite ville en celle de Pignerol, lui cinquième", four men from Dunkirk to Calais and five from Calais to Pignerol, the fifth being the prisoner (as quoted by Petitfils 2003, p. 244 n. 11). Petitfils, Noone, the historian Michel Vergé-Franceschi and Sonnino accept it; the document itself was not consulted for this report, and Petitfils's transcription is the only one in print. And the precautions are severe but not unique. On 10 March 1674 Louvois sent Saint-Mars another prisoner, "who, though obscure, is still a man of consequence", to be treated "in the same way as the prisoner M. de Vauroy brought you", and Le Tellier, Louvois's father and his predecessor as war minister, writing on 23 March, said why: he was "un fripon insigne qui, en matière fort grave, a abusé des gens considérables" (Ravaisson, III, pp. 176–177). The ministry stated a reason for the prisoner of March 1674, and no surviving letter states one for Eustache.
For eleven years the man is one prisoner among several in Saint-Mars's charge at Pignerol, and the letters treat him both as a servant and as a man whose past must not be spoken of. In August 1671 he is ill, and Saint-Mars writes that "il me donne assez d'occupation pour lui souhaiter la santé" (Laloy, pp. 109–110). On 20 February 1672 Saint-Mars, unable to find servants willing to be shut up with his prisoners, proposes "ce prisonnier qui est dans la tour, et que vous m'avez envoyé par M. le major de Dunkerque" as a valet for Lauzun: "Je ne pense pas qu'il dît à M. de Lauzun d'où il sort, après que je lui aurais défendu; je suis sûr qu'il ne lui dirait pas aussi aucune nouvelle, ni ne me demanderait point de sortir de sa vie, comme font tous les autres" (Ravaisson, III, pp. 117–119). No reply is printed, but the answer is known from what followed. On 30 December 1673: "Pour le prisonnier de la tour, que M. de Vauroy m'a amené, il ne dit rien, il vit content comme un homme tout à fait résigné à la volonté de Dieu et du Roi" (Ravaisson, III, pp. 174–175).
Sa Majesté approuve que vous donniez, pour valet, à monsieur Foucquet, le prisonnier que le sieur de Vauroy vous a conduit; mais, quelque chose qui puisse arriver, vous debvez vous abstenir de le mettre avec monsieur de Lauzun, ni avec qui que ce soit, autre que monsieur Foucquet. […] C'est-à-dire que vous pouvez donner le dit prisonnier à M. Foucquet, si son valet venoit à luy manquer et non autrement.
[11 March] pour quelque raison que ce puisse estre, il ne faut point que vous luy donniez le prisonnier que le sieur de Vauroy vous a amené, qui ne doit servir, en cas de nécessité, qu'à monsieur Foucquet.
"His Majesty approves that you give as valet to M. Fouquet the prisoner whom the sieur de Vauroy conducted to you; but, whatever may happen, you must abstain from putting him with M. de Lauzun, or with anyone whatever other than M. Fouquet. […] That is to say, you may give the said prisoner to M. Fouquet if his valet should fail him, and not otherwise." "[11 March] for whatever reason it may be, you must not give him [Lauzun] the prisoner the sieur de Vauroy brought you, who is to serve, in case of necessity, only M. Fouquet."
What it fixes. The letter fixes the distinction the state drew between the two prisoners. Fouquet, condemned for life, could hear whatever the man knew, and Lauzun, whose imprisonment was expected to end, could not. Laloy (p. 111) and Lair (p. 454) both read the clause this way, and the next four years of orders bear it out.
Fouquet's valet Champagne had died "at Notre-Dame de septembre" (1674 by Lair's dating, 1675 by Laloy's), and Eustache took his place beside the older valet La Rivière. In December 1678 the King prepared to soften Fouquet's prison, and before doing so put one question to him.
Sa Majesté est en disposition de donner dans peu de temps des adoucissements fort considérables à votre prison; mais, comme elle désire auparavant être informée si le nommé Eustache, que l'on vous a donné pour vous servir, n'a point parlé, devant l'autre valet qui vous sert, de ce à quoi il a été employé auparavant que d'être à Pignerol, Sa Majesté m'a commandé de vous le demander, et de vous dire qu'elle s'attend que sans aucune considération vous me manderez la vérité de ce que dessus, afin qu'elle puisse prendre les mesures qu'elle trouvera plus à propos sur ce qu'elle apprendra par vous que ledit Eustache aura pu dire de sa vie passée à son camarade.
"His Majesty is disposed to grant shortly very considerable softenings of your prison; but as she wishes first to be informed whether the man named Eustache, who was given you to serve you, has not spoken, before the other valet who serves you, of what he was employed at before being at Pignerol, His Majesty has commanded me to ask you, and to tell you that she expects that without any consideration you will tell me the truth of the above, so that she may take the measures she finds most fitting on what she learns from you of what the said Eustache may have said of his past life to his comrade."
What it fixes. The secret was an employment, "ce à quoi il a été employé", and a past life. Bernard Caire reported at Cannes in 1987 that the minute of this letter first read "what he had seen" and was corrected to "how he was employed" (as reported by Noone and by Petitfils; the minute itself was not consulted). The King's concern in 1678 was whether the secret had reached La Rivière, and in April 1680, sixteen months later, La Rivière was shut up with Eustache.
Fouquet's answer is lost. On 17 February 1679 Louvois told him that "Sa Majesté veut bien se remettre à vous de la conduite qu'il faudra tenir à l'égard d'Eustache Danger" (Ravaisson, III, pp. 209–210), and the memoir (the written instructions) of 20 January 1679 that opened Fouquet's and Lauzun's apartments to each other and to visitors carries two paragraphs about "le nommé Eustache": whenever Lauzun or any stranger comes into Fouquet's room, Saint-Mars is to withdraw Eustache and not put him back "until there is no one there but him and his old valet"; when Fouquet walks in the citadel Eustache stays in the room, and follows only when Fouquet walks alone with his old valet (Delort 1829, I, pp. 280–285). On 15 February 1679: "Le Roy se remet à vous de régler avec monsieur Foucquet, comme vous jugerez à propos, ce qui regardera la seureté de la personne du nommé Eustache Danger, vous recommandant sur tout de faire en sorte qu'il ne parle à personne en particulier" (I, pp. 286–288). On 13 September 1679 Louvois asks for "des nouvelles de la santé d'Eustache Dangers" (Ravaisson, III, p. 212; the final s is visible in the photograph of K 120 no. 277).
Fouquet died on 23 March 1680. Saint-Mars reported the death, a hole he had found between Fouquet's and Lauzun's rooms, and his judgement that Lauzun knew most of the important things Fouquet had known "et que le nommé la Rivière ne les ignore pas". Louvois's reply of 8 April 1680 is the document on which the later chain of custody depends.
Que vous persuadiez à monsieur de Lauzun, que les nommés Eustache d'Angers, et le dit la Rivière, ont été mis en liberté, et que vous en parliez de mesme à tous ceux qui pourroyent vous en demander des nouvelles; que cependant vous les renfermiez tous deux dans une chambre, où vous puissiez réspondre à Sa Majesté qu'ils n'auront communication avec qui que ce soit, de vive voix, n'y par éscrit, et que monsieur de Lauzun ne pourra point s'apperçevoir qu'ils y sont renfermez.
"That you persuade M. de Lauzun that the men named Eustache d'Angers and the said La Rivière have been set at liberty, and that you speak the same way to all who might ask you news of them; that meanwhile you shut them both up in a room where you can answer to His Majesty that they will have no communication with anyone whatever, by word of mouth or in writing, and that M. de Lauzun will not be able to perceive that they are shut up there."
What it fixes. From April 1680 the two valets are one unit, held under a fiction of release. The same letter fixes the other prisoners' subsistence at four livres a day each. On 10 July 1680 Louvois writes that it will suffice to have "les habitans de la tour d'en bas" confessed once a year, and asks "comment il est possible que le nommé Eustache ayt fait ce que vous m'avez envoyé, et où il a pris les drogues nécessaires pour le faire" (Delort 1825, pp. 261–262): the pair are the inhabitants of the lower tower, and the name Eustache is used for one of them three months after the order. Lair, Laloy, Funck-Brentano and Mongrédien read it so; Iung, who needed the lower tower for other prisoners, did not.
One letter of this spring has been used to argue that the chain of custody breaks here. On 12 March 1680 Louvois told Saint-Mars that the King did not intend "que vous payez à monsieur Foucquet les gages de celuy de ses valets qui est mort" (Delort 1829, I, p. 316; K 120 no. 299, photographed on masque-de-fer.com). Jean-Marc Dabos reads this as the death of Eustache and builds on it a thesis that the masked man was Fouquet himself, his death of 23 March being a fiction. The rest of the file tells against that reading, though the alternative reading is itself an inference. Fouquet's valets had been deprived of wages since January 1670 for their infidelity, and La Rivière asked for his arrears in September 1679 (Iung, p. 196); the most economical reading is that Saint-Mars had asked whether Fouquet should be paid the arrears of the valet who had died, Champagne, and that Louvois said no. The letter of Saint-Mars that Louvois was answering is not in the editions, so that reading is not documented; what is documented is that four weeks later Louvois names both Eustache and La Rivière as living men to be shut up, orders Fouquet's furniture disposed of, releases the body to Fouquet's son (8 and 9 April), and the Visitation Sainte-Marie convent in Paris entered his burial in its register on 28 March 1681 (Lair, II, pp. 473–474).
Lauzun was released in April 1681 and Saint-Mars asked for another post. The King gave him Exilles, a fort in the Alps between Pignerol and Briançon, and decided which prisoners would go with him.
[Sa Majesté] a trouvé bon de vous accorder le gouvernement d'Exilés […] où elle fera transporter ceux des prisonniers qui sont à vostre garde, qu'elle croira assez de conséquence pour ne les pas mettre en d'autres mains que les vostres. […] un mémoire des réparations absolument nécessaires pour le logement des deux prisonniers de la tour d'en-bas, qui sont, je crois, les seuls que Sa Majesté fera transférer à Exiles. Envoyez-moi un mémoire de tous les prisonniers dont vous estes chargé, et marquez-moy, à costé, ce que vous savez des raisons pour lesquelles ils sont arrestés. A l'esgard des deux de la tour d'en-bas, vous n'avez qu'à les marquer de ce nom, sans y mettre autre chose.
"[His Majesty] has thought fit to grant you the government of Exilles […] where she will have transported those of the prisoners in your keeping whom she judges of enough consequence not to put them in other hands than yours. […] a memoir of the repairs strictly necessary for the lodging of the two prisoners of the lower tower, who are, I believe, the only ones His Majesty will transfer to Exilles. Send me a memoir of all the prisoners in your charge and note beside each what you know of the reasons for their arrest. As for the two of the lower tower, you need only mark them by that name, without putting anything else."
What it fixes. The letter counts the two valets, and not Mattioli, as the prisoners "of consequence" in 1681, and the reason for their arrest was not to be written even in a memoir to the minister.
On 9 June the two are to leave Pignerol "dans une litière" under the escort of Saint-Mars's company, the rest of the prisoners staying under the lieutenant Villebois at two écus (six livres) a day "for the food of these three prisoners", and Mattioli's clothes are to be carried to Exilles "to be able to return them to him if ever His Majesty ordered him set free" (Delort 1825, p. 269). Delort read that last clause as proof that Mattioli went to Exilles. Saint-Mars's own letter to the abbé d'Estrades of 25 June 1681 says the opposite: "j'aurai en garde deux merles que j'ai ici, lesquels n'ont point d'autres noms que messieurs de la tour d'en bas; Matthioli restera ici avec deux autres prisonniers", "I shall have in my keeping two blackbirds I have here, who have no other names than the gentlemen of the lower tower; Mattioli will stay here with two other prisoners" (Ravaisson, III, pp. 212–213, from the d'Estrades papers). Louvois then delayed the move so that it would not look contrived: the repairs are to be slowed "so as to have a pretext not to leave until about the first days of October", "observant de vous conduire de manière qu'il ne paroisse point d'affectation" (22 July 1681; Delort 1825, p. 274). The reason for the delay was Catinat, the officer who was hidden at Pignerol under a false name while France negotiated the secret purchase of Casale, a fortress in northern Italy, from the Duke of Mantua. No letter gives the day of departure; the first letter from Exilles is of 4 December 1681.
At Exilles the pair were held in the manner Saint-Mars described on 12 July 1681 before leaving: they would not leave their room to hear mass, a lieutenant would sleep above them, two sentries would watch the tower day and night, and the old curé of Exilles could confess them but was forbidden "on the King's behalf to know who these prisoners are, nor their names, nor what they have been" (Roux-Fazillac, p. 110; Iung, pp. 398–399). On 14 December 1681 Louvois allowed them clothes, "mais il faut que les habits durent trois ou quatre ans à ces sortes de gens-là", "for that sort of people" (Topin, p. 332). On 2 March 1682 the King wanted the prisoners "que l'on nommoit à Pignerol de la Tour d'en bas" to have no dealings with anyone, not even the garrison (Iung, p. 400). On 16 April 1684 Louvois asked Saint-Mars for news of "vos prisonniers" and "ce que vous savez de la naissance du nommé La Rivière et de l'aventure par laquelle il fut mis au service de feu M. Foucquet" (Iung, p. 402): La Rivière was at Exilles, and the minister did not know who he was. On 30 January 1685 what the prisoners had told Saint-Mars was "d'aucune conséquence" (Iung, p. 403). On 7 June 1685 one of them wanted to make his will (Iung, p. 403). On 23 December 1685: "Mes prisonniers sont toujours malades et dans les remèdes. Du reste, ils sont dans une grande quiétude" (Roux-Fazillac, p. 113). On 9 January 1686 Louvois complained that Saint-Mars should have named "quel est celuy de vos prisonniers qui est devenu hydropique", and on 3 November 1686 allowed the dropsical one to be confessed "lorsque vous verrez apparence d'une prochaine mort. Jusque-là il ne faut pas que lui ou son camarade aient aucune communication" (Iung, p. 404).
The correspondence is incomplete at this point. Saint-Mars's letter of 5 January 1687 announcing a death is lost. Louvois's reply of 13 January survives: "J'ai reçu votre lettre du 5 de ce mois, par laquelle j'apprends la mort d'un de vos prisonniers" (Iung, p. 405; P. 231, v. 779). From Saint-Mars's next letter, 20 January 1687, the prisoner is referred to in the singular, "mon prisonnier", and in the singular in every later letter.
Everything after January 1687 is documented for one man. Whether that man is the valet of 1669 or Fouquet's valet La Rivière is not stated in any surviving letter, and the reader should know that every author who names the survivor is inferring. Lair (1890, II, p. 479) wrote that the dropsical prisoner who died on 4 January 1687 was La Rivière and that Saint-Mars was left with "Eustache Danger"; Funck-Brentano and Petitfils follow him; Iung, who thought Eustache had stayed at Pignerol, made the dead man the Jacobin, a Dominican friar held at Pignerol since 1674; Roux-Fazillac, who had no letter between December 1685 and January 1687, asked "est-ce Matthioly ou le moine?" and left it open. The date of death is also an inference: 4 January is deduced from the letter of the 5th, and Funck-Brentano's "end of December 1686" is a mis-citation of Lair.
Three later letters bear on the identity. Jules Lair drew the conclusion first (1890, t. II, pp. 485–486): the masked man was "un des deux Messieurs de la Tour d'en bas", La Rivière died at Exilles in January 1687, and the survivor was Danger. Georges Mongrédien restated it from the later letters (Le Masque de fer, 1952, pp. 196–197 and 222: "nous avons démontré qu'il est mort à Exiles en 1687"), and Mongrédien himself noted (p. 230) that Lair's whole identification presupposes that the 1703 prisoner never left Saint-Mars's custody, which no letter states in so many words before 1698. This report reaches the same conclusion by the same route, and assigns it a probability.
Lorsque vous aurez quelque chose à me mander du prisonnier qui est sous vostre garde depuis vingt ans, je vous prie d'user des mesmes précautions que vous faisiez quand vous les donniez à M. de Louvois.
"When you have something to tell me about the prisoner who has been under your guard for twenty years, I beg you to use the same precautions you used when you gave them to M. de Louvois."
A new minister, writing from his father's registers, identifies the one prisoner who requires special precautions by the length of his custody. The valet of 1669 had been in Saint-Mars's hands for twenty-two years. La Rivière had come to Pignerol with Fouquet in January 1665, twenty-six years before, as a free servant, and had been a prisoner in his own right for eleven years, since April 1680. "Vingt ans" is a round number in either case, but twenty-two rounds to twenty, and a clerk working from a file that opens with the dispatches of July 1669 would arrive at that figure. Editors who preferred other candidates read the number to fit them: Iung made it eighteen years for a prisoner of 1673, Topin seventeen for the Jacobin of 1674, and Paul Lacroix, who held for Fouquet (1836), twenty-seven.
Vous n'avez point d'autre conduite à tenir à l'égard de tous ceux qui sont confiés à votre garde, que de continuer à veiller à leur sûreté, sans vous expliquer à qui que ce soit de ce qu'a fait vostre ancien prisonnier.
"You have no other conduct to keep towards all those entrusted to your guard than to continue to watch over their safety, without explaining to anyone what your old prisoner has done."
Two readings. Topin's transcription in the original spelling reads "de ce qu'a fait", what he has done. Iung's modernised text reads "ce que fait", what he does. Topin's is the more literal of the two and agrees with the King's order of 1669 ("mal satisfait de la conduite") and Louvois's letter of 1678 ("ce à quoi il a été employé"). The original in the war archives (series A1, vol. 1392, p. 171) would settle it.
The third piece of evidence is what the letters of the whole file are about. From 1669 to 1680 the minister's letters are about Eustache: his cell, his windows, his health, whether he has been spoken to, whether he has spoken, to whom he may be lent, what Fouquet knows of his past. La Rivière appears in them as Fouquet's servant, to have his wages stopped, to be enquired after in 1684 because the minister did not know where he came from, and to be shut up in 1680 because he might have heard what Eustache and Fouquet knew. Nothing in the record makes La Rivière a man who had "done" something. After 1687 the state builds a prison for the survivor at a cost of 6,926 livres (16 March and 17 August 1687), refuses to name him in writing, moves him to the Bastille "so that he be seen and known by no one", and keeps him there for five years. That treatment fits the prisoner the ministry had been protecting since 1669 rather than La Rivière, who had been shut up only because he might have heard.
Three points can be argued for La Rivière, and this report judges each of them weak. The prisoner who wanted to make a will in June 1685 is more likely a servant with wages owed than "un valet" arrested with nothing. The state had treated the two as one unit since 1680, so the special prison of 1687 proves only that the survivor was one of the pair and does not say which. And Barbezieux, a minister of twenty-three, may have used "vingt ans" loosely. Taking these together, this report puts the probability that the survivor of January 1687 was the valet of 1669 at 85 per cent and the probability that he was La Rivière at 15 per cent. Mongrédien treated the point as settled and Petitfils does not discuss it as a difficulty; that is the one place where this report is less confident than Lair, Mongrédien and Petitfils.