By the time Vigée le Brun scandalized the masses by exhibiting the Queen in what appeared to be her underwear in 1783, the queen and women of quality had been going en chemise for several years and not just in the privacy of their boudoir. Like oil and water, the classes didn't mix and this was the first time the populace had been exposed en masse to the depravities of the aristocracy. Ironically, the shocking bit was the lack of formality shown by a monarch already famous for flouting tradition. The Queen (capitol Q) was shown without any of the outward symbols and trappings of her position, culturally naked, and appearing en negligée was taken as an insult to her position as mother of the people.
Le Brun was forced to remove her painting from the public eye, but like all scandals, they inspire more than they deter and the chemise gown became the symbolic frock of the 1780's.
The earliest versions were formed much like actual chemises, consisting of four pieces of rectangular cotton muslin yardage and gathered at the neck, just under the bosom, and again at the natural waist, which was then belted with very broad silk sash and tied in back. Sleeves were full, and also tied at two or three places, stopping at or just below the elbow. This was frequently finished off at the neck with a double or tripple collar. By 1790 classical lines and revolutionary ardor had taken the beau monde by storm and women of fashion and culture appeared in portraits and the salons as idolized Roman matrons or Greek godesses. This was primarily achieved by losing the gathered waist and broad sash and the fullness of the sleeves. Sleeves were either close fitted into the armhole, and no longer than just above the elbow, or non-existant, a la toga. It wasn't until the later Empire period that the poofy sleeve often associated with this style was introduced.As revolutionary sentiment reached a fever pitch (and mostly among the artistocracy, I might add), the pinnacle of outward expression of revolutionary fervor was the Roman simplicity and egalitarian nature of the the white muslin gown.
Initially quite modest by our standards, by 1791 the simple frock was every bit as daring as can be imagined. Up until 1800 it could be worn with or without short-waisted corsets. There are numerous portraits of young women of the demi-monde going bare-breasted or the semi-transparent. This effect was often enhanced by dampening the dress with water so it would cling to the figure like a classical statue. In order to preserve some semblance of modesty knitted knee length knickers would be worn... the first underwear maybe? And can be clearly seen in this Incroyable et Merveilleuse painting by Boilly.
Continued: For the most extreme and exotic versions of the fashion, please see the Incroyable & Merveilleuse gallery! (coming soon!)