Myriad journeys and associations, diplomatic, commercial and personal, linked the Ottoman Empire to Western Europe. They were reflected not only in consulates and embassies, and in the movement of products such as coffee, tobacco and antiquities, but in less familiar forms: wallets or letter cases made in Constantinople for Europeans. The Sadberk Hanım Museum in Istanbul and the Ömer M Koç Collection have mounted an exhibition of these splendid objects, with a lavish catalogue.

Turkish artisans belonged to fraternities, or ahi, of which the tanners’ guild was the most powerful. (The word ahi derives from the name of a 13th-century mystic, Ahi Evran, himself a tanner.) After the Conquest in 1453, some 360 tanneries were built outside the walls of Istanbul, lingering, as did their uniquely noxious smell, into the 1980s. Used in shipbuilding, saddlery, armoury and campaign tents, leather was of such military value that a ban on exporting leather goods was only relaxed in the 17th century.

From about 1650 to 1850, in the two great ports of Istanbul and Smyrna (Izmir), pieces of goatskin were tanned into leather, dyed, sewn together, covered in cloth and adorned with silk, metal or satin embroidery, to make rectangular wallets.

“No one can sew leather as neatly as they do,” the French diplomat and naturalist Pierre Belon said of the Turks in the 1550s, and the patterns in thread of swirling leaves, flowers and fruit are indeed extremely attractive. Often dyed madder red, they usually follow Western rather than Ottoman models.

These symbols of Ottoman–European interaction were nimbly adorned with the word “Constantinople”, a date, a name (usually male), and occasionally with a coat of arms and a coronet. Spanish, English, Greek and, above all, French names attest to the variety of visitors to the Empire. Here are some of the inscriptions:

“Harbert Randoph from your obliged Cousin B. Randoph Smyrna 25th June 1669”; “Elizabeth Wall, Smyrna Anno Domini 1686”; “Mr Le Comte De Caraman, Constantinople 1781”; “Marqués de San Leonardo, Constantinople 1775”

Occasionally the inscriptions also spell out the attached emotions:

“Ubi amor ibi oculus” (Where there is love, the eye will be watching); “Pour mon Ami, Constantinople 1779”; “La Reconnaissance à L’Amitié” (Souvenir of Friendship)

The wallets were given as presents, or used to store letters and official documents, such as the Ottoman travel permit every foreign traveller needed. Some had more than one compartment: for lettres répondues (answered letters), lettres à répondre (letters awaiting reply) and notes diverses. Locks were often added later in Paris. Wallets might also be made for Ottomans and bear a date in Western numerals, an inscription in Ottoman Turkish and a sultan’s cypher, or tuğra.

Letter wallets are on display in London, at the Victoria and Albert Museum, and in New York, at the Met. Those with poor embroidery were probably made elsewhere and sewn with spurious “Constantinople” labels to make them easier to sell.

Perhaps the most interesting example bears the name “Comte de Vergennes” and the date 1774. As ambassador to Constantinople (1755–68) and foreign minister (1774–87), Charles Gravier, comte of Vergennes, strengthened France’s Ottoman alliance. He obviously retained a taste for Ottoman objects, as his wallet was made after his departure. Vergennes knew the city so well that – almost unprecedented for a Western ambassador – he married a local woman: Anne Duvivier, widow of Francesco de Testa, one of a celebrated family of dragomans who had lived in the city since before the Conquest. They were unconventional enough to live together before marriage. One of their sons was named Constantine after the city of his birth. Dazzling portraits in the Pera Museum of the couple in Ottoman dress, painted by Antoine de Favray just before they left the city in 1768, are, like the wallets, unequivocal tributes to Ottoman–French friendship.

As foreign minister, Vergennes helped France win the American War of Independence against Britain in 1783. He is just as much a Founding Father of the United States as his friend Jefferson.

He may also have encouraged and subsidised the dragoman Mouradgea d’Ohsson’s splendid three-volume opus Tableau général de l’Empire othoman, published in Paris from 1787 (see Cornucopia 63), which sought the regeneration of the Ottoman Empire. Vergennes was trusted by both Louis XVI and much of French opinion. If this great minister had not died in 1787, the French Revolution might have taken a very different course. Allied to a reformed French monarchy, Selim III might have been able to start radical reforms in the Ottoman Empire 30 years before Mahmud II. And he might have avoided death by the sword in the Topkapı in 1808.

The catalogue, by Hülya Bilgi, is available in full and abbreviated editions