The Mozart family left London on 24 Jul 1765, after a stay of fifteen months. Following a brief stop in Canterbury (where they may have given a concert, although this remains uncertain), they spent several days at Bourne Place in nearby Bishopsbourne. Leopold’s original intention had been to return to Paris, but the Dutch envoy in London had followed them to Canterbury with a special request from Princess Carolina, sister of William V, Prince of Orange, the stadtholder of the Dutch Republic. The princess, who was eight months pregnant, very much wished to hear the Mozart children, whose fame was now widespread (see our entry for 18 Sep 1765). Leopold felt obliged to accede to her request, “als sie wissen” (he wrote to Lorenz Hagenauer) “daß man einer Schwangeren Frauen nichts abschlagen solle” (“as you know that one should not refuse a pregnant woman anything”; Briefe, i:201). On 1 Aug the Mozarts made the trip across the English Channel from Dover to Calais, intending to head northeast from there towards The Hague.

The Mozarts’ itinerary between 1 Aug and 11 Sep 1765 is poorly documented. Leopold sent no letters to Hagenauer between 9 Jul (his last from London) and 19 Sep (his first from The Hague). In his letter of 19 Sep 1765 he gives only a highly compressed account of the interval between their arrival in Calais and their arrival in Lille (where they stayed for around four weeks because Wolfgang had a bad cold and Leopold suffered a period of dizzy spells and vomiting), and he gives no precise dates at all for the six weeks between their arrival in Calais and their arrival in The Hague. Until recently, no other documents were known bearing on this portion of the Mozarts’ European tour.

Two documents have recently come to light that fill some of the gaps in our knowledge. One newly discovered item is an inscription on the back of an exemplar of the famous Delafosse engraving of the Mozarts, based on Carmontelle’s equally famous watercolor portrait (on the engraving and watercolor see our entry for 21 Jan 1765). The inscription places the Mozarts in Dunkirk on 9 and 10 Aug 1765, several days later than previously thought (see our entry on the inscription). The other new item, transcribed here, is an entry in the manuscript diary of Emmanuel de Croÿ-Solre, Duc de Croÿ (1718–1784): Croÿ writes that the Mozart children—he does not identify them by name, but the identification is beyond doubt—performed at a party he held in Calais on Sun, 4 Aug 1765. The significance of Croÿ’s diary entry for Mozart scholarship was first recognized by Catherine Sprague, and Cliff Eisen published an article about it in the Mozart-Jahrbuch 2014 (Eisen 2015).

The Mozarts arrived in Calais on Thu, 1 Aug 1765. Leopold’s travel notes show that they lodged at the Hôtel d’Angleterre, managed by Pierre Dessin (Briefe, i:196; Schurig 1920, 30). Dessin had formerly run the “Lion d’Argent” in Calais, but that hotel was destroyed by fire in the night of 24–25 Sep 1764 (Demotier 1856, 283), and he quickly re-established himself in the Hôtel d’Angleterre, a large complex in the Rue Royale. Dessin was soon to become famous in his own right from Laurence Sterne’s depiction of him in A Sentimental Journey, published in 1768, based on Sterne’s own experience in Calais in 1762 (Sterne 1768, 21 and passim). The Hôtel d’Angleterre long remained the preferred lodging of the many distinguished visitors passing through Calais, including royalty, aristocrats, and such prominent figures as Benjamin Franklin and Thomas Jefferson. An eighteenth-century guide for British travelers writes of the Hôtel d’Angleterre:

[…]                                    But no hotel
in France is equal to that from which I
now write. Monsieur Dessein knows the
goùt of both nations, and blends them with
propriety; and he has the advantage of a
palace as it were, to do it in.
[Thicknesse 1770, 259]

Croÿ’s manuscript diary, Mémoires de ma vie, consists of 6700 pages in 41 volumes; it is held by the library of the Institut de France. Portions of the diary were published by Grouchy and Cottin in 1906–1907, but that edition does not include the passage referring to the Mozarts. The reference was apparently first published by Dion (1987, 104–105), but was unknown to Mozart scholars until it was uncovered by Sprague.

Emmanuel de Croÿ, Duc de Croÿ, Prince du Saint Empire, de Solre et de Meurs (1718–1784), stemmed from an ancient and illustrious noble family that was said ultimately to trace its roots back to Prince Marc of Hungary, who had settled in France in the twelfth century (see Dictionnaire de la Noblesse 1772, 372ff; see also the article on the House of Croÿ on English Wikipedia). Emmanuel was born on 23 Jun 1718 in Condé-sur-l’Escaut (where Josquin had spent the last years of his life). The Château de l’Ermitage (the Hermitage) in Condé-sur-l’Escaut remained Croÿ’s principal and beloved residence throughout his life. Young Croÿ distinguished himself as a military commander during the War of the Austrian Succession (1740–1748), by the end of which he had achieved the rank of maréchal de camp (field marshal). For a portion of the Seven Years’ War (1756–1763) he was commander in Artois, Picardie, Calaisis (Pas-de-Calais), and Boulonnais (Dion 1987, 12), and responsible for the defense of the corresponding portions of the French coast. Croÿ sometimes made his headquarters in Calais in a house belonging to the Marquise d’Alembon, and he played a role in evaluating and renovating the fortifications at Calais, Dunkirk, and other coastal towns under his command (see our entry for 9–10 Aug 1765).

Croÿ’s party on 4 Aug 1765 very likely took place in the same house that he had used during the war, and where he continued to stay on his later visits to Calais. Central Calais was largely obliterated in the Second World War, and the location of the house is not entirely certain. However, a nineteenth-century reference work on historical inscriptions in Pas-de-Calais transcribes the text of a plaque on the house at 15 Rue Saint-Denis, at that time (1886) the British consulate in Calais. The plaque is reported to have read:

A footnote to the inscription identifies the house as having belonged to the Marquise d’Alembon (Croÿ himself did not own a house in Calais until near the end of his life). Although this inscription is misleading in its implication that Croÿ lived in the house continuously between 1762 to 1783—after the end of the Seven Years’ War, he visited Calais relatively infrequently—it is at present our best evidence of the location of the performance by the Mozart children in 1765. A Baedeker guide from 1909 confirms that 15 Rue Saint-Denis was indeed the address of the British consulate at that time (Baedeker 1909, 3). The house in question may have been the one shown in the map above on the right (east) side of Rue Saint-Denis with the elegantly curved inner wing. It can be seen below in an aerial photograph from 1935.

The party on 4 Aug 1765 was not the only one that Croÿ gave in Calais. The Gazette de France reported, for example, that Croÿ had given a magnificent dinner on 7 Sep 1762 for the Duc de Nivernois and the Duke of Bedford, whose paths crossed in Calais as they were traveling to London and Paris respectively to negotiate a treaty ending the war between France and Britain:

⁣          De Calais, le 8 Septembre 1762.
    Le Duc de Nivernois est arrivé le 6 en
cette Ville, & a reçu les honneurs qu’on rend
ordinairement aux Ambassadeurs du Roi.
Le Duc de Bedford y est débarqué le lende
main 7, & a reçu les mêmes honneurs. Le
Prince de Croy, qui commande ici, a donné
à dîner aux deux Plénipotentiaires, & les a
traités avec la plus grande magnificence. Le
Duc de Bedford a pris aujourd’hui la route de
Paris; & le Duc de Nivernois doit s’embar-
quer ce soir sur le Yacht de Sa Majesté Bri-
tannique, pour passer en Angleterre.
[Gazette de France, no. 74, 13 Sep 1762]

⁣          From Calais, 8 September 1762.
    The Duc de Nivernois arrived in this city
on the 6th and received the honors that
are ordinarily given to the ambassadors of
the King. The Duke of Bedford landed here
the next day, the 7th, and received the same
honors. The Prince de Croÿ, who is the
commander here, gave a dinner for the
two plenipotentiaries, and treated them with
the greatest magnificence. The Duke of
Bedford set out today for Paris, and the
Duc de Nivernois plans to embark this
evening to go to England on the yacht
of His British Majesty.

Croÿ also seems to have made a point of expressing his gratitude to his soldiers and to the general population of Calais by holding parties and dinners for them. This good-natured noblesse oblige is evident in his description of the ball that he held at the end of his party on 4 Aug 1764.

On 18 Feb 1741 Croÿ married Angélique-Adélaide d’Harcourt, with whom he had two children who survived to adulthood. His wife died on 7 Sep 1744, and Croÿ never remarried, which may help explain the role that Duchesse Louise-Françoise-Pauline de Montmorency-Luxembourg (1734–1818) appears to have played in assisting Croÿ with the organization and hosting of his party in 1765. The Duchesse de Montmorency is listed in Leopold Mozart’s travel notes immediately before Croÿ (Briefe, i:196; Schurig 1920, 39), and he mentions the two in the same sentence in his letter to Hagenauer on 19 Sep 1765 (Briefe, i:201).

Croÿ refers to the Mozart children playing a piece that Wolfgang had written for keyboard four-hands. Eisen (2015, 167ff) speculates on the implication of this passage for the question of the authenticity of the sonata K. 19d and the divertimento in C major, K. deest, but concludes that the matter remains unresolved.

Croÿ gives the ages of Wolfgang and Nannerl 8 and 15; the were actually 9 and 14 at the time of Croÿ’s party.

We now know that the Mozarts were in Calais from 1 to 4 Aug 1765, but we still do not know exactly when they left Calais on the next leg of their journey. The newly discovered inscription on an exemplar of the Delafosse print places them in Dunkirk on 9 and 10 Aug. Dunkirk is around 40 km from Calais by road, and the trip would likely have been made within just one day. Thus the newly discovered dates for the Mozarts’ stay in Dunkirk suggest that they may have remained in Calais until as late as 8 Aug. If this is correct, then they spent a week in a town where at one time they were thought to have remained only overnight (see, for example, Briefe, commentary to Leopold’s travel notes, v:140).