Guillaume Kornmann (born 1741,
Strasbourg
Strasbourg ( , ; ; ) is the Prefectures in France, prefecture and largest city of the Grand Est Regions of France, region of Geography of France, eastern France, in the historic region of Alsace. It is the prefecture of the Bas-Rhin Departmen ...
; died 1795,
Paris
Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...
) was a French banker. He is best known for the particularly sensational trial of his wife (prosecuted by
Beaumarchais
Pierre-Augustin Caron de Beaumarchais (; 24 January 1732 – 18 May 1799) was a French playwright and diplomat during the Age of Enlightenment. Best known for his three Figaro plays, at various times in his life he was also a watchmaker, invent ...
) in the 1780s.
In 1774, Kornmann married Catherine Marie Foesch, a young Swiss heiress, who bore him two children. They settled in Paris, where he managed his uncle's bank. The couple did not get on well, and Kornmann allowed his wife to take a lover, as long as she kept things in order. The lover was a certain Daudet de Jossan, a confidant of the powerful de Montbarey, Minister for War and magistrate for Strasbourg. But soon, the minister resigned, and the young man suddenly became much less respectable. Furthermore, Madame Kornmann, who did not hesitate to be seen with him in a scandalous way, threatened to demand a separation from her husband (as divorce did not yet exist). Fearing he would lose his wife and particularly her dowry, Guillaume Kornmann, who in the meantime was almost ruined, obtained a warrant from the police commissioner and had his adulterous wife arrested, then pregnant by her lover.
Thus, on the night of 3–4 August 1781, his wife was taken to Douai, a disciplinary institution on the Rue de Bellefond that housed "lost" and mad women. On the insistence of mutual friends, Beaumarchais rescued Madame Kornmann (whom he did not yet know). Thus began the Kornmann Affair. Once freed, she tried unsuccessfully to obtain a legal separation from her husband, arguing that her scandalous detention justified it.
The cheated husband decided to press charges against his spouse and her lover for adultery, against Beaumarchais and Police Commissioner Lenoir for defamation and as accessories to adultery. He took his friend
Nicolas Bergasse
Nicolas Bergasse (; born 24 January 1750 in Lyon – died 28 May 1832 in Paris) was a French lawyer, philosopher, and politician, whose activity was mainly carried out during the beginning of the French Revolution during its early Monarchiens ph ...
, a fellow disciple of
Anton Mesmer, as his lawyer.
Beaumarchais was declared innocent by order of the
Parlement of Paris
The ''Parlement'' of Paris () was the oldest ''parlement'' in the Kingdom of France, formed in the 14th century. Parlements were judicial, rather than legislative, bodies and were composed of magistrates. Though not representative bodies in the p ...
the 2 April 1789. Kornmann and his lawyer Bergasse were ordered to pay him damages but public opinion remained largely in their favour. In 1793 Madame Kornmann finally obtained a divorce, which had been permitted by the law of 20 September 1792.
1741 births
Businesspeople from Strasbourg
1795 deaths
French bankers
{{France-business-bio-stub