Michel de Castelnau, Sieur de la Mauvissière ( 1520–1592) was a French soldier and diplomat, ambassador to Queen Elizabeth I. He wrote a memoir covering the period between 1559 and 1570.Gustave Hubault, Michel de Castelnau ambassadeur en Angleterre (Paris, 1856).
Life He was born in La Mauvissière (now part of Neuvy-le-Roi, Indre-et-Loire), Touraine about 1520. He was a son of Jean de Castelnau and Jeanne Dusmesnil, one of a family of nine children.Estelle Paranque, Elizabeth through Valois Eyes (Palgrave Macmillan, 2019), p. 13. His grandfather, Pierre de Castelnau, had been Equerry (Master of the Horse) to Louis XII.
Endowed with a clear and penetrating intellect and remarkable strength of memory, he received a careful education, capped off with travels in Italy and a long stay at Rome. He then spent some time in Malta and afterwards entered the army. His first acquaintance with war was in the campaigns of the French in Italy. His abilities and his courage won him the friendship and protection of Charles, Cardinal of Lorraine, who took him into his service.
In 1557 a command in the navy was given to him, and the cardinal proposed to get him knighted. This, however, he declined, and then rejoined the French army in Picardy. Various delicate missions requiring tact and discretion were entrusted to him by the Constable, Anne de Montmorency, and these he discharged so satisfactorily that he was sent by the king, Henry II, to Scotland with dispatches for Mary of Guise, the mother of Mary, Queen of Scots, who was betrothed to the Dauphin (afterwards Francis II).
From Scotland he passed into England in 1559, and treated with Queen Elizabeth respecting her claims on Calais, a settlement of which was effected at the congress of Le Cateau-Cambrésis. He was next sent as ambassador to the princes of Germany, for the purpose of prevailing upon them to withdraw their favor from the Protestants. This embassy was followed by missions to Margaret of Austria, governess of the Netherlands, to Savoy, and then to Rome, to ascertain the views of Pope Paul IV in regard to France. Paul having died just before his arrival, Castelnau used his influence in favor of the election of Pius IV. Returning to France, he once more entered the navy, and served under his former patron. It was his good fortune, at Nantes, to discover the earliest symptoms of the Conspiracy of Amboise, which he immediately reported to the government.
After the death of Francis II in December 1560, he accompanied Mary, Queen of Scots, to Scotland.John Guy, Mary Queen of Scots (Fourth Estate, 2009), p. 132.Claude-Bernard Petitot, Mémoires de Messire Michel de Castelnau: Seigneur de Mauvissière, 33 (Paris, 1823), pp. 123-131 He remained with her a year, during which time he made several journeys into England in an attempt to bring about a reconciliation between Mary and Queen Elizabeth. The wise and moderate counsel that he offered to the former were unheeded.
In 1562, as a consequence of the civil war in France, he returned there. He was employed against the Protestants in Brittany, was taken prisoner in an engagement with them and sent to Havre, but was soon after exchanged. In the midst of the excited passions of his countrymen, Castelnau, who was a sincere Roman Catholic, maintained a wise self-control and moderation, and by his counsels rendered valuable service to the government. He served at the siege of Rouen, distinguished himself at the battle of Dreux, took Tancarville, and contributed in 1563 to the recapture of Havre from the English.
England and Scotland in the 1560s During the next ten years Castelnau was employed in various important missions: first to Queen Elizabeth to negotiate a peace. In March 1564, Castelnau visited Scotland to encourage Mary, Queen of Scots, to marry a French Duke.William Barclay Turnbull, Letters of Mary Stuart (London, 1845), p. 15. After Mary married to Lord Darnley in July 1565, he was involved in diplomatic responses to her troubles during the Chaseabout Raid and he visited her at Holyroodhouse.John Guy, The Life of Mary Queen of Scots (Fourth Estate, 2009), pp. 234–236: Alexandre Teulet, Relations Politiques, 2 (Paris, 1862), pp. 245–258 He returned to Edinburgh following the murder of David Rizzio.Claude-Bernard Petitot, Mémoires de Messire Michel de Castelnau: Seigneur de Mauvissière, 33 (Paris, 1823), pp. 354-356
In April 1566, he went to see Mary at Edinburgh Castle during her pregnancy.Allan J. Crosby, Calendar State Papers Foreign Elizabeth, 1566–1568 (London, 1871), p. 51 no. 297: John Guy, The Life of Mary, Queen of Scots: My Heart is my Own (Fourth Estate, 2009), p. 240: Joseph Bain, Calendar State Papers Scotland, vol. 2 (Edinburgh, 1900), pp. 276-7. Castelnau brought letters for Darnley, who wrote to Catherine de' Medici to thank her, taking the opportunity to insist he was innocent of the "horrible crime" of Rizzio's murder.Joseph Stevenson, The History of Mary Stewart by Claude Nau (Edinburgh: Paterson, 1883), p. cxxiii.
Wars of Religion Castelnau was sent to the Duke of Alba, the new governor of the Netherlands. On this occasion he discovered the project formed by the Prince of Condé and Admiral Coligny to seize and carry off the royal family at Monceaux (1567). After the battle of St. Denis he was again sent to Germany to solicit aid against the Protestants; and on his return he was rewarded for his services with the post of governor of Saint-Dizier and a company of orderlies. At the head of his company he took part in the battles of Jarnac and Moncontour.
Ambassador in London In 1572 he was sent to England by Charles IX to allay the excitement created by the St. Bartholomew's Day Massacre, and the same year he was sent to Germany and Switzerland. In September 1575, he was reappointed by Henry III ambassador to Queen Elizabeth, as a successor to Bertrand de Salignac de la Mothe-Fénelon, and he remained at her court for ten years.John Guy, The Life of Mary, Queen of Scots: My Heart is my Own (Fourth Estate, 2009), p. 450: Frances Yates, John Florio: The Life of an Italian in Shakespeare's England (Cambridge, 1934), p. 64. During this period in London, Castelnau used his influence to promote the marriage of Queen Elizabeth with the Duke of Alençon, with a view especially to strengthen and maintain the alliance of the two countries but Elizabeth made so many promises only to break them that at last he refused to accept them or communicate them to his government.
In England, Castelnau's wife Marie had difficult pregnancies and miscarriages and she crossed and recrossed the English channel to see physicians in France, at great expense.John Bossy, Giordano Bruno and the Embassy Affair (Yale, 1991), p. 20: Alexandre Teulet, Papiers d'état, vol. 2 (Edinburgh, 1851), pp. 694-5 Elizabeth I was godmother to their son and daughter,Elaine Kruse, "A Network of Honour and Obligation: Elizabeth as Godmother", Anna Riehl Bertolet, Queens Matter in Early Modern Studies (Palgrave Macmillan, 2017), p. 195. and gave christening gifts including, in January 1577, a gilt double cup decorated with leopard heads.Arthur Jefferies Collins, Jewels and Plate of Queen Elizabeth I: The Inventory of 1574 (London: British Museum, 1955), p. 554 no. 1443.
The Italian philosopher Giordano Bruno was a member of the Castelnau household in London for two years. Bruno dedicated three dialogues on the infinite nature of the universe to Castelnau.Diego Pirillo, 'Tasso at the French Embassy', Jason Powell & William T. Rossiter, Authority and Diplomacy from Dante to Shakespeare (Ashgate, 2013), p. 139. A suggestion that Bruno leaked confidential information from the embassy in this period, proposed by the historian John Bossy, has not gained much acceptance.Ingrid D. Rowland, Giordano Bruno: Philosopher / Heretic (University of Chicago, 2008), p. 299: Jill Kraye, 'John Bossy on Giordano Bruno', Heythrop Journal, 33 (1992), pp. 324–7: John Bossy, Giordano Bruno and the Embassy Affair (Yale, 1991). John Bossy's conclusion that Laurent Feron was an embassy mole, passing information to Francis Walsingham remains unchallenged.Jade Scott, Captive Queen: The Decrypted History of Mary, Queen of Scots (London: Michael O'Mara Books, 2024), p. 31. Another Italian writer and linguist, John Florio, worked for Castelnau between 1583 and 1585. Florio was also the tutor of his daughter Katherine Maria.Frances Yates, John Florio: The Life of an Italian in Shakespeare's England (Cambridge, 1934), pp. 61-64: Sophie Crawford Lomas, Calendar State Papers Foreign Elizabeth, 20 (London, 1921), p. 28: Carole Levin, The Reign and Life of Queen Elizabeth I: Politics, Culture, and Society Springer, 2022), p. 131.
Mary, Queen of Scots, and letters in code
In London, Castelnau de Mauvissière resided at Salisbury Court near Fleet Street or Butcher Row near the Strand.John Bossy, Under the Molehill: An Elizabethan Spy Story (Yale, 2001), pp. 61, 248-9. Mary, Queen of Scots, sent letters to him from captivity at Sheffield Manor and Castle. He presented her letters to Elizabeth I.William K. Boyd, Calendar State Papers Scotland, vol. 6 (Edinburgh, 1910), pp. 57-8, 194-5, 217-8. Castelnau's wife, Marie, sent Mary fabrics to make clothes,David Templeman, Mary, Queen of Scots: The Captive Queen in England (Exeter, 2016), p. 151: William Turnbull, Letters of Mary Stuart, Queen of Scotland (London: Pickering, 1845), p. 284. and helped to find women to join her household. Mary called her "ma commère", meaning her namesake.Alexandre Labanoff, Lettres de Marie Stuart, vol. 5 (London, 1852), p. 121: Agnes Strickland, Letters of Mary, Queen of Scots, vol. 2 (London, 1842), p. 63. Mary regarded Castelnau's daughter as her godchild and mignonne. She sent her a jewel which had been a present to her from Henry II of France.Agnes Strickland, Letters of Mary, Queen of Scots, vol. 3 (London, 1843), pp. 142-3: William Barclay Turnbull, Letters of Mary Scots (London, 1845), pp. x-xi.
What Mary wants Castelnau showed some of Mary's letters to William Fowler, and he informed Francis Walsingham. Mary had written that she was not Elizabeth's prisoner, but a captive of the Lord Treasurer, William Cecil.William K. Boyd, Calendar State Papers Scotland, vol. 6 (Edinburgh, 1910), p. 689 no. 724. Mary wrote secret letters in cipher to Castelnau complaining of her bad treatment, in 1581 asking for French money, soldiers, and artillery to be supplied according to the traditional Auld Alliance between England and Scotland.Alexandre Teulet, Papiers d'état, vol. 2 (Paris, 1851), p. 461 Frustrated by the apparent lack of support from France, Mary wrote to Castelnau in July 1581 that she could choose to negotiate with Spain instead.Jade Scott, Captive Queen: The Decrypted History of Mary, Queen of Scots (London: Michael O'Mara Books, 2024), p. 215.
In 1582, Mary hoped that Castelnau's negotiations would lead to her release and an "association" with her son. In the short term, she wanted Castelnau to obtain permission for visits to Buxton for her health.P. J. Holmes, 'Mary Stewart in England', Innes Review, 38:38 (1987), pp. 197, 212: A. Labanoff, Lettres de Marie Stuart, vol. 5 (London, 1852), pp. 340, 356, 456: Calendar State Papers Scotland, 1581-1583, vol. 6 (Edinburgh, 1910), p. 13 no. 25: Alexandre Teulet, Papiers d'état, vol. 2 (Edinburgh, 1851), p. 357. Mary's physician, Dominique Bourgoing, kept Castelnau informed of Mary's illnesses.William Boyd, Calendar State Papers Scotland, 1574-1581, vol. 5 (Edinburgh, 1907), p. 404-5 no. 482. Castelnau also interceded with Elizabeth I for delivery of clothes, letters, and preserves from France.William Boyd, Calendar State Papers Scotland, vol. 5 (Edinburgh, 1907), p. 210 no. 218.