Who the valet was
The record says little about the man before Pignerol. He was entered as Eustache d'Auger or Danger or d'Angers; the ministers used the Christian name alone from 1678 onward ("le nommé Eustache"), which Laloy took to mean a nickname given at his entry into prison and Bernard Caire, after examining the handwriting of the originals, took to mean that Eustache was the surname and "d'Angers" a place of origin. He was a valet, or at least treated as one for thirty-four years, and was arrested by the major of Dunkirk, probably at Calais. He was a Catholic who heard mass and confessed, and was ill in 1669, 1671 and 1687 and "always valetudinary" in 1688. He could serve, and Fouquet found him acceptable for five years. In 1680 he did something with drugs that Louvois found hard to believe possible in a cell. Saint-Mars wrote in 1673 that he said nothing and "lived content". He died after a day's illness in 1703.
Every proposed identification of his master argues from the dates of events near the arrest. The arrest fell in the weeks after the execution of the Huguenot conspirator Roux de Marsilly (22 June 1669), the recall of the abbé Pregnani, an Italian astrologer whom Louis XIV had sent to Charles II's court, from his mission (May to July), and the first exchanges of the secret negotiation between Louis XIV and Charles II that Madame, Henrietta of England, carried and that produced the secret treaty of Dover of June 1670, in which Charles II promised to join France against the Dutch and to declare himself a Catholic. Vauroy was posted at Dunkirk, and the road from Calais is the route from England. The Scottish writer Andrew Lang (1903) made him Marsilly's valet Martin, and the report of Colbert de Croissy, the French ambassador in London, of 1 July 1669 that Martin refused to come to France, followed by the order of Lionne, the foreign minister, of 13 July to drop the matter, dispose of that. Arthur Barnes, a Catholic priest (1908), made him Pregnani, who died in Rome in 1678 or 1679. Maurice Duvivier, in a book of 1932, made him Eustache Dauger de Cavoye, a disgraced nobleman of the right name, and Mongrédien published in 1953 the two letters Cavoye wrote in 1678 and about 1679 from Saint-Lazare, a house of correction in Paris where he had been held since 1668. Théodore Iung (1873) connected him to the poisoners, ten years before the Chambre ardente, the special court that tried the poisoning cases of 1679 to 1682. Petitfils's first book (1970) made him a valet of Colbert hired by Louvois for a poisoning in December 1668, hidden from the King and from Colbert; the King's own signature on the order of 28 July 1669 and Colbert's payment of Vauroy's journey tell against it, and Petitfils had dropped it by 1991. Émile Laloy (1913, pp. 199–200), after abandoning Pregnani, kept the man himself, "à peu près sûrement un prêtre", and put the secret "plutôt dans 'ce à quoi il avait été employé' que dans sa personnalité même"; that is the first statement of the reading followed in this report.
The two hypotheses now in the field are these.
- Jean-Christian Petitfils, Le Masque de fer: entre histoire et légende (Perrin, 2003; revised 2004). Eustache Danger was "un humble valet affecté au service de Madame", who had handled or carried secret papers concerning Charles II's conversion and the alliance against the Dutch, talked too much, and was seized at Calais by Vauroy with three archers (as summarised by his reviewers Stéphane Genet, writing in 2003 for H-Net, an online network of scholarly reviews, and Diego Venturino, in the journal Dix-huitième siècle in 2005, and in his own chapter "Du danger du secret au secret de Danger"). Petitfils reads the name as the surname Eustache with a place of origin, and offers one man from the Calais registers as a possible match: Gaspard Eustache, son of Jehan Eustache and Jossine Cléché, born 20 December 1643 and baptised on the 27th at Notre-Dame de Calais (Archives départementales du Pas-de-Calais, 5 MI 193 R28; Petitfils 2003, p. 167). Nothing but the surname and the town connects that child to the prisoner, and a birth in 1643 gives sixty at death against the register's "forty-five or thereabouts". Petitfils also sets the limit of his own thesis: the prisoner's life in prison "nous prouve que son affaire, quelle qu'elle ait pu être, n'était pas vraiment de la plus haute importance". The mask, in Petitfils's account, was "une mystification montée de toute pièce par le geôlier" and "ne fut jamais demandé par les ministres". Genet raised three objections which Petitfils's book, in the parts that could be read, does not remove: why forbid the man's name if he was nobody; why keep him after 1672, when the Dover secret had lost its value; and why he was so docile.
- Paul Sonnino, The Search for the Man in the Iron Mask: A Historical Detective Story (Rowman and Littlefield, 2016). Eustache Dauger was a valet of Antoine-Hercule Picon, the man who managed Mazarin's fortune, and "the most trusted of those men", to whom Picon had entrusted "some of the most sensitive details of Mazarin's peculations" (the historian Julius Ruff's review for H-France, an online review journal, 2016). The secret was that Mazarin had built part of his fortune by cheating Henrietta Maria, Charles I's French-born queen, and Charles I himself, with the connivance of Louis XIV; the trigger was that Louis was courting Charles II in 1669; the offence was that Dauger "blabbed at the wrong time", perhaps in drink. Sonnino had spent a decade on the candidacy of Claude Imbert, an agent of the cardinal de Retz, Mazarin's old enemy, until he found Imbert alive and free in 1675, 1679 and 1681; the Picon thesis dates from 2003, when Sonnino found Picon's marriage contract of 30 December 1662 (Archives nationales, notarial archive, Minutier central, XVI/477), and grew out of his archival work on the three versions of Mazarin's will (French Historical Studies, 2014). Sonnino states that Dauger was "neither the valet of Nicolas nor of Basil" Fouquet, and that he "found no trace of individuals with the name of Auger or Dauger who might have provided the Picons with a suitable valet". The historian David Parrott's review (French History, 2017) says the fair thing: "Dauger's status as one of Picon's valets rests on a balance of probabilities rather than written evidence."
Both theses explain the timing with the same events and the place with the same road, and both are consistent with the one substantive clue the letters give, that the secret was an employment. They differ on whether the secret would have expired. Madame's negotiation had become public policy by 1672, whereas Mazarin's money, on Sonnino's account, implicated the King himself. That is Sonnino's structural advantage and Petitfils's weakness, and Petitfils meets it by saying that the prisoner was hidden "non parce qu'il était connu, mais parce qu'il était inconnu et, au fond, sans importance depuis les années 1680" (Venturino's summary). The letter of 12 May 1681, in which the King moves the two valets as the prisoners "of consequence" and leaves Mattioli behind, is hard to square with a prisoner who no longer mattered. No document names a valet of Picon or a servant of Madame. This report gives the Madame hypothesis about 25 per cent and the Picon hypothesis about 20 per cent, and leaves more than half the probability with an employment the surviving papers do not point to at all. These two figures are judgements about events for which no document survives.
Why thirty-four years
That question contains three: what the state was protecting, why the man was never released, and where the mask came from. The letters describe the kind of secret being protected but never state its content. They also show how a man once imprisoned remained so, and where the mask originated.
What was being protected
The orders of 1669 forbid the prisoner's communication with others and say nothing about his being seen. The dungeon's windows were to give on no approachable place and its doors were to keep the sentries from hearing; Saint-Mars alone was to carry his food; he was threatened with death for speaking of anything but his needs. In March 1670 the precaution is repeated as "ne puisse voir ni estre veu de personne, et ne puisse parler à qui que ce soit". In 1675 he may serve Fouquet, who would never leave, and never Lauzun, who would. In 1678 the King wants to know whether he has told La Rivière "ce à quoi il a été employé auparavant que d'être à Pignerol". In 1679 he is to be withdrawn whenever anyone but Fouquet and the old valet is in the room, and is to "speak to no one in private". In 1680 La Rivière, who "n'ignore pas" Fouquet's secrets, goes into the same room under the same fiction of release. In 1681 the reason for their arrest is not to be written even for the minister. In 1697 Saint-Mars is to explain to no one "ce qu'a fait vostre ancien prisonnier". The consistent object across twenty-eight years is that a valet's account of his own past employment should reach nobody, and in particular nobody who would return to court.
The file also rules three things out. His face was of no concern to anyone until Saint-Mars made it one in 1687. He was treated as a valet throughout, in furniture, clothing and wages. And the ministry did not treat his regime as unique. Louvois sent the prisoner of March 1674 to be treated "de la même façon que le prisonnier que M. de Vauroy vous a amené", and Le Tellier called that one "un fripon insigne qui, en matière fort grave, a abusé des gens considérables". The ministry applied the same regime to at least one other prisoner held for what he knew, and stated the grounds in his case. In a file of more than a hundred letters that gives grounds for other prisoners, no minister gives grounds for Eustache.
Why he was never released
Louis XIV's state prisons had no procedure for releasing a man held for what he knew, and this file shows none being used. Louvois's own letter of 17 December 1669 states the principle: if Saint-Mars removed La Rivière from Fouquet's service, he was to keep him seven or eight months first, "afin que, s'il avoit pris des mesures pour porter des nouvelles de son maître, elles soient si vieilles en ce temps-là qu'elles ne puissent en rien préjudicier". The length of the delay was matched to how long the news would stay useful. Of the state prisoners in Saint-Mars's Pignerol donjon, Fouquet died there in 1680, the Jacobin about 1694, Dubreuil, a spy held since 1676, on the island about 1697, and Mattioli, on the reading given above, on the island in 1694; Lauzun was released because a duchess, the King's cousin Mademoiselle de Montpensier, bought his freedom by settling estates on the duc du Maine, the King's illegitimate son. After Louvois died in 1691 the orders continued unchanged. Barbezieux's first letter asks for the same precautions as before; in 1694 the ministry does not know the name of the prisoner who has died at Pignerol and asks Saint-Mars for it in cipher; in 1697 the standing order is to continue. Whether Barbezieux or Pontchartrain ever knew what the man had done, the letters do not say. And the man's jailer had every reason to keep him. Saint-Mars was paid 500 livres a month at Pignerol and kept that pay at Exilles "moyennant quoi vos appointemens seront aussi forts que ceux des gouverneurs des grandes places de Flandre" (12 May 1681); he received a gratification of 15,000 livres in 1679 and 2,000 écus for his furniture in 1698; his free company, the soldiers raised and paid to guard his prisoners, and his lieutenants went where his prisoner went; and in January 1688 he was advertising his new cells to the minister "pour quand vous auriez des prisonniers à vouloir mettre en toute seureté". This does not require the secret to have remained dangerous, only that no one with authority ever ruled that it was not, and the file records no such ruling. Mongrédien (1952, pp. 194, 200 and 229) added that the reasons for keeping him multiplied inside the prison: after 1675 he had heard Fouquet's confidences, in 1680 he had handled the "drogues", and Lauzun had been told he was gone. Petitfils (1991, 2003) and Caire (1991) both concluded that the original secret "n'est pas aussi important qu'on l'a imaginé" and that Saint-Mars inflated it; Genet's question, why keep a man whose secret had lost its value, is answered by the practice of the prisons rather than by the content of the secret.
Where the mask came from
No minister ordered a mask. The word does not occur in any of the hundred and eighty letters and register entries read for this report from 1669 to 1703 until du Junca's entry of 18 September 1698, where it is Saint-Mars's practice ("lequel il fait tenir touiours masqué"). The documented sequence runs as follows. January 1687: Saint-Mars proposes a chair covered in oilcloth so that no one can see the prisoner, and Louvois leaves the means to him. May 1687: "personne au monde ne l'a vu … chacun cherche à deviner qui peut être mon prisonnier". September 1687: the bishop of Agde's newsletter reports a steel mask in a sedan chair and orders to kill the prisoner if he says his name. January 1688: Provence says he is Beaufort or Cromwell's son. July 1698: Barbezieux, in the King's name, tells Saint-Mars to take his precautions "pour empescher qu'il ne soit veu ny conneu de personne", and in August the King approves the precautions Saint-Mars listed in a letter now lost. September 1698: the prisoner enters the Bastille masked and is kept so, in black velvet, for the walk to mass. 1751: Voltaire turns the velvet into a mask "dont la mentonnière avait des ressorts d'acier". Petitfils and Noone both concluded that the mask was Saint-Mars's device, and this report confirms it with one qualification: the King approved in August 1698 whatever precautions Saint-Mars had proposed for the journey, so the mask, if it was among them, had the King's general sanction from then on. Saint-Mars had written in 1687 that his precautions made everyone try to guess who the prisoner was, and the guesses of 1688 were a duke and Cromwell's son. A velvet mask on a prisoner no one in Paris had seen invited the same guessing.
The strongest counter-cases
- Mattioli (Funck-Brentano 1894): the burial name against six documented failures, above all Barbezieux's letter of 10 May 1694. Put at 3 per cent.
- La Rivière as the survivor of 1687: undocumented either way; against him the "twenty years" of 1691, the "what he has done" of 1697 and the subject matter of the file. Put at 15 per cent within the chain, 14 per cent overall.
- Brugnon's death of 1693: Papon's hearsay of 1778 against the ministers' continuous "ancien prisonnier" of 1696 to 1698. Put at about 5 per cent together with the other ways the 1698 prisoner could be a different Pignerol prisoner.
- The royal brother (Voltaire to Marcel Pagnol): no document, and the valet's furniture, service, bed and clothes against it. No separate share of the probability is assigned to it beyond the 5 per cent residue.
- Fouquet (Dabos 2025): the 12 March 1680 wages letter read as a death, against the letter of 8 April 1680 that names both valets alive, the release of the body, and the Visitation burial entry of 1681.
What would overturn this
- Saint-Mars's letter of 5 January 1687, or any Exilles account, naming the prisoner who died. If it names Eustache, the Bastille prisoner was La Rivière and the first two verdict lines change places.
- A burial or garrison record of Sainte-Marguerite between 1687 and 1698 recording the death of the prisoner of the new cell, which is what Brugnon's reconstruction of the island register claims to establish. It was not available here.
- The original of Barbezieux's letter of 17 November 1697 (Service historique de la Défense, A1 vol. 1392, p. 171) reading "ce que fait" rather than "ce qu'a fait", which would remove one of the three supports for the 1669 identification of the survivor.
- Any document naming the master or employment of "Eustache" in 1669: Vauroy's reimbursement order in the Mélanges Colbert as Brugnon described it, Fouquet's sealed reply of January 1679, or the Calais notarial records Sonnino cites. Such a document would settle the second question and might change the third.
- The minute of Louvois's letter of 19 July 1669 read in a hand other than the scribe's, or the name shown to have been added later, which would bear on whether the name was real.
What is new here, and what is not
The identification is not new. Jules Lair established it in 1890 from the K 120 letters ("Il était Français, catholique, valet de profession. Tout porte à croire qu'il s'appelait réellement Eustache Danger", t. II, p. 454), Loiseleur had already shown in 1882 that the masked man of 1687 came from Exilles and could not be Mattioli, Mongrédien in 1952 eliminated every Pignerol prisoner but Mattioli and the valet and showed that La Rivière died in 1687, while declining to choose between the two ("Si oui, c'est Dauger, si non, c'est Matthioli", p. 231), Petitfils has defended the valet since 1970, and Noone (1988), Sonnino (2016) and Wilkinson (2021) start from him. The reading of the name as Danger or d'Angers is Lair's and Caire's; the arrest at Calais is Brugnon's (1987); the steel-mask report of 1687 was printed by Azéma (1963) and brought into the debate by Brugnon; the deleted "ce qu'il a vu" in the minute of 23 December 1678 is Caire's find (1987, 1991). The reading of the mask as the jailer's device is Noone's and Petitfils's, and the judgement that the secret was small is Caire's and Petitfils's. The refutations of Martin, Cavoye and Bulonde belong to Laloy (1913), Mongrédien (1953) and Batiffol (1894). The observation that the secret was an employment rather than an identity is Laloy's (1913, p. 200) and Caire's.
What this report adds is smaller and of three kinds. First, the whole printed record for 1669 to 1703 has been transcribed into one hundred and eighty dated entries with each edition's archive reference and the variants between editions tabulated, so that the chain of custody can be checked line by line rather than trusted; the entries, the candidate file, the script that produces the table and the script that produces the headline and its sensitivity are published with this case. Second, the 1687 identification is reported as an inference with a probability rather than as an established fact. Lair and Petitfils state the identity of the 1687 survivor as a fact, and Mongrédien wrote that he had demonstrated it; here it carries a probability and a published sensitivity, and the Bastille identification is reported at 78 per cent rather than as certain. Nothing in this report is new evidence: no document unknown to the printed editions was found, and the three points that follow are new readings of old evidence. Third, three small points that were not found in the works read, several of which were read only in fragments: the ministers' continuous use of "ancien prisonnier" from Saint-Mars's letter of January 1696 to the orders of 1698 as the answer to Brugnon's thesis of a death in 1693; the letter of 12 March 1680 on the dead valet's wages read as Champagne's wage arrears rather than as a death in 1680, an inference from the surrounding letters rather than a documented exchange; and the variant "ce qu'a fait" against "ce que fait" in the letter of 17 November 1697 flagged as a reading that bears on the argument and that the original would settle. The comparison of the 1669 orders with the 1674 order to treat another prisoner "in the same way" is in Laloy and Ravaisson; its use here, to show that the ministry could state a reason and did not, is this report's.
On the second and third questions the answer is that nobody knows. This report has not identified the valet either. It has measured how far the two current identifications rest on documents, and neither rests on a document that names the prisoner.
What was not read
- Petitfils (2003 and 2004) and Sonnino (2016), the two books that defend the current identifications, were not read in full. That is the largest gap in this report. Petitfils was reached through about 1,050 search-service fragments of the lending copy (130 characters each, from some 400 queries), his reviewers Genet (2003) and Venturino (2005) in full, a 2005 interview and a third-party summary; Sonnino through about 1,000 fragments, the reviews by Ruff (2016) and Parrott (2017, by summary) and by Publishers Weekly, and three interviews. The reviews of Sonnino in the Journal of Modern History, the Catholic Historical Review and the American Historical Review, and his 1992 article on Claude Imbert, were not obtainable. The quotations from both books above are therefore fragments, exact as far as they go; the objections raised may be answered in pages not seen. The two authors' own statements of their theses, in their words, are collected in the working notes published with this case.
- Mongrédien's Le Masque de fer (1952) was read in 3,439 snippets from Gallica, the Bibliothèque nationale's digital library, each carrying the printed page number, plus its full table of contents, and his 1953 article in full; his conclusion (pp. 221–231) is quoted from those snippets. Noone (1994), Wilkinson (2021), Thompson (1987) and Macdonald (2005) were read in search fragments only. Petitfils's 1970 book is known only from four contemporary reviews. Duvivier (1932) was not read; Bazeries and Burgaud (1893) were read through Batiffol's review and Laloy.
- The proceedings of the Cannes colloquium of 1987 (Brugnon, Caire) and of Pinerolo 1974 were not obtainable; the proceedings of a second conference, at Pinerolo in 1991 (Caire, Petitfils, Noone), were read in fragments. Brugnon's reconstruction of the island register (1992, a typescript at the Arsenal) and Caire's articles of 1988, 1997 and 1998 were not obtainable. Vauroy's reimbursement order, the deleted words in the minute of 23 December 1678 and the Saint-Lazare order of 17 August 1678 are known only through those authors' reporters.
- No original manuscript was consulted. The war-office registers (Service historique de la Défense, series A1), the K 120 file and the Arsenal registers were read through the editions; six letters were checked against photographs. Iung, Topin, Lair and Funck-Brentano differ on dates, folios and words, and where they differ the report says so rather than choosing on authority.
- The Bibliothèque nationale's Gallica site refused automated access throughout, which is why Mongrédien 1952 was read in snippets and the newsletter of 4 September 1687 only in Dabos's photograph.
- The probabilities are the author's judgements about the weight of the documents. The arithmetic that produces the headline is stated so that a reader who weighs the 1691 letter differently can redo it.
Sources
Manuscript series (read through the editions below)
- Archives nationales, K 120 (cartons des rois; Saint-Mars's file of letters received, 1669–1681) and K 129. Photographs of K 120 nos 132, 275, 277, 299 and 302 at masque-de-fer.com (Jean-Marc Dabos), harvested 14 September 2026.
- Service historique de la Défense, Vincennes, série A1 (the "Dépôt de la guerre" registers cited by Iung and Topin as "P. x, v. y"), vols 234, 618, 684, 779–783, 1034, 1242–1247, 1392, 1431–1432.
- Bibliothèque de l'Arsenal, mss. 5133 and 5134 (du Junca's registers of entries and exits).
- Bibliothèque nationale, papiers d'Estrades (Saint-Mars to d'Estrades, 1681, printed by Ravaisson III).
- Bibliothèque Sainte-Geneviève, ms. 1477, fol. 396 v° (manuscript newsletter of 4 September 1687 attributed to Louis Fouquet, bishop of Agde; photograph at masque-de-fer.com; printed by X. Azéma, Un prélat janséniste, Louis Foucquet, évêque et comte d'Agde, Paris, Vrin, 1963, p. 150, not seen).
- Bibliothèque nationale, Mélanges Colbert, vol. 282, fol. 276 v° (reimbursement of Captain de Vauroy's journey, 1669; found by S. Brugnon; quoted by Petitfils 2003, p. 244 n. 11; not seen).
- Register of burials of Saint-Paul, 20 November 1703 (destroyed 1871; facsimile in Topin, 5th ed., 1878, and Revue encyclopédique, 1 April 1894).
Editions of the correspondence
- Roux-Fazillac, Recherches historiques et critiques sur l'homme au masque de fer (Paris, an IX/1801). Bibliothèque municipale de Lyon, Numelyo, BML_00GOO0100137001102795544.
- J. Delort, Histoire de l'homme au masque de fer (Paris, 1825); Histoire de la détention des philosophes et des gens de lettres à la Bastille et à Vincennes, t. I (Paris, 1829). archive.org/details/histoiredeladte05delogoog.
- F. Ravaisson, Archives de la Bastille, t. III (Paris, 1866), t. VII–XI (1874–1880). archive.org/details/archivesdelabast03rava, archivesdelabast07rava, archivesbastille10rava.
- Th. Iung, La Vérité sur le Masque de fer (Paris, 1873). archive.org/details/lavritsurlemasq00jung.
- J. Loiseleur, Trois énigmes historiques (Paris, 1882). archive.org/details/troisnigmeshist00loisgoog.
- M. Topin, L'Homme au masque de fer, 6th ed. (Paris, 1883); English translation (London, 1870).
- J. Lair, Nicolas Foucquet, t. II (Paris, 1890). archive.org/details/nicolasfoucquetp02lairuoft.
- F. Funck-Brentano, "L'homme au masque de velours noir, dit le Masque de fer", Revue historique 56 (1894), pp. 253–303; Légendes et archives de la Bastille (Paris, 1901). archive.org/details/lgendesetarchi00funcuoft.
- E. Laloy, Le Masque de fer: Jacques Stuart de la Cloche, l'abbé Prignani, Roux de Marsilly (Paris, 1913). archive.org/details/masqueJacques00lalo.
- H. Griffet, Traité des différentes sortes de preuves qui servent à établir la vérité de l'histoire (Liège, 1769; ed. 1770). archive.org/details/traitedesdiffere00grif.
- G. A. Ellis, The True History of the State Prisoner commonly called the Iron Mask (London, 1826). archive.org/details/truehistorystat00elligoog.
- Journal du marquis de Dangeau, t. III (Paris, 1854). archive.org/details/journaldumarquis03dang.
Scholarship
- L. Batiffol, review of Burgaud and Bazeries, Bibliothèque de l'École des chartes 55 (1894), pp. 359–360. archive.org/details/bibliothquedel55sociuoft; Persée.
- A. Lang, The Valet's Tragedy and Other Studies (London, 1903). Project Gutenberg 2073.
- A. S. Barnes, The Man of the Mask (London, 1908). archive.org/details/manofmaskstudyin00barnuoft.
- M. Duvivier, Le Masque de fer (Paris, 1932). Not read.
- G. Mongrédien, Le Masque de fer (Paris, Hachette, 1952, 256 pp.), Gallica ark:/12148/bpt6k3357084j, read in 3,439 page-numbered snippets and the table of contents; "Deux documents inédits sur le Masque de fer", XVIIe siècle 17–18 (1953), pp. 55–58. archive.org/details/xviie-siecle_1953_17-18.
- S. Brugnon, "L'identité de l'homme au masque de fer", pp. 27–38, and B. Caire, "Eustache et son secret", pp. 41–49, in Il y a trois siècles, le Masque de fer. Actes du colloque international, Cannes, 12–13 septembre 1987 (Cannes, 1989; 2nd ed. 1996). Not obtained; known through Petitfils, Noone, Sonnino, Wilkinson and Madry.
- B. Caire, "Le secret d'Eustache Danger", pp. 176–207, and J.-C. Petitfils, "La double légende et le secret d'État", pp. 210–237, in La Maschera di Ferro e il suo tempo. Atti del convegno internazionale di studio, Pinerolo, 13–15 settembre 1991 (Pinerolo, Alzani, 1992). archive.org lending item pinerololamasche0000unse; search fragments only.
- S. Brugnon, Reconstitution du registre d'écrou des prisonniers de l'île Sainte-Marguerite à compter du 30 avril 1687 et jusqu'au 19 mars de l'année 1704 (typescript, 1992), Bibliothèque de l'Arsenal, fol. Z 2753. Not obtained.
- J. Noone, The Man Behind the Iron Mask (Stroud, Alan Sutton, 1988; rev. ed. 1994). archive.org lending item manbehindironmas0000noon; search fragments only.
- J.-C. Petitfils, L'Homme au masque de fer (Paris, Perrin, 1970). Not read; known through the reviews in Le Figaro littéraire (27 April 1970), Historia 289 (December 1970) and the Bulletin critique du livre français 296 (1970).
- J.-C. Petitfils, Le Masque de fer: entre histoire et légende (Paris, Perrin, 2003, 310 pp.; coll. tempus, 2004). archive.org lending items lemasquedeferent0000peti and lemasquedeferent0000peti_h1r0; about 1,050 search fragments; reviews by S. Genet (H-Net, October 2003) and D. Venturino (Dix-huitième siècle 37, 2005, pp. 645–646, Persée).
- P. Sonnino, "On the Trail of the Iron Mask: The Candidacy of Claude Imbert", Proceedings of the Western Society for French History 19 (1992), not obtained; "The Three Testaments of Cardinal Mazarin", French Historical Studies 37 (2014), pp. 421–436, doi:10.1215/00161071-2689643, abstract only; The Search for the Man in the Iron Mask: A Historical Detective Story (Lanham, Rowman and Littlefield, 2016, xiv + 269 pp.). archive.org lending item searchformaninir0000sonn; about 1,000 search fragments; reviews by J. R. Ruff (H-France Review 16, 2016, no. 258, h-france.net/vol16reviews/vol16no258Ruff.pdf), D. Parrott (French History 31, 2017, p. 122, doi:10.1093/fh/crw073, by summary) and Publishers Weekly (30 November 2015); interviews in The UCSB Current (27 April 2016) and Live Science (2016).
- S. Madry, "The Valet: The Marquis de Louvois's Invited Guest", Cahiers du dix-septième 17 (2016), pp. 1–27. Read in full.
- J. Wilkinson, The Man in the Iron Mask: The True Story of Europe's Most Famous Prisoner (New York, Pegasus, and Stroud, Amberley, 2021). archive.org lending item 9781643137421; publisher's pages and search fragments only.
- H. Thompson, The Man in the Iron Mask (London, 1987), and R. Macdonald, The Man in the Iron Mask (London, 2005). Search fragments only.
- J.-M. Dabos, masque-de-fer.com (2024–2025), 52 pages harvested, with photographs of the originals listed above.
Working files published with this case: the transcriptions and notes, the fixed points and the candidate file, the two scripts (fixed_points.py, which produces the candidate table, and probability.py, which produces the headline and its sensitivity), and the source texts.