The Chevalier d’Éon was a French diplomat and spy living in Britain during the reign of George III. They spent spent much of their life presenting as a man and after 1777, presented as a woman. Though it is tempting to view d’Éon as transgender in a twenty-first-century sense, it is important to recognise this terminology did not exist during their lifetime. 
This book, which caused a scandal in the French court, was written and first published by d’Éon when still presenting as a man. It describes their career serving as plenipotentiary minister, essentially interim ambassador, in Britain in the 1760s and makes several accusations regarding the conduct of the new ambassador the comte de Guerchy.
D’Éon and Guerchy hated one another. Prior to the latter's arrival in London, d’Éon had become popular among London society and expected to keep the position when the new ambassador arrived. Instead, Guerchy stripped d’Éon of their post and demoted them to secretary. The rivalry continued with d’Éon refusing to return to France when asked and accusations that Guerchy had attempted to poison them at a dinner held at the ambassador's residence.
The publication of this book, which, in addition to attacking Guerchy, also revealed secret correspondence between the Embassy and the French court, made d’Éon very popular in London and Guerchy's carriage was often attacked in the streets.
In the aftermath, d’Éon fled into exile and began writing an autobiography and guide to administration in which it is apparent that they viewed themselves as a woman, but had instead been raised as a boy (RCINs 1025793-6). In 1766, Guerchy was recalled from his position and d’Éon had their pension reinstated. In 1777, the French king Louis XVI legally permitted d’Éon to present as a woman, so long as they continued do so for the remainder of their life.
D’Éon returned to London permanently in 1785 and became an instant celebrity. In 1787, they participated in a famous fencing match at Carlton House against the Chevalier de Saint-Georges, an event that was immortalised in contemporary prints and paintings (for example RCIN 400636). Following the French Revolution, d’Éon lost their diplomatic pension and was forced to sell many of their possessions. They died in poverty in May 1810. A medical examination carried out after their death found that while they had male genitalia, their body also possessed female characteristics. This conclusion indicates that d’Éon may have been intersex.