1864 Napoleon III, Empress Eugénie, and retinue from La réception des ambassadeurs du Siam à Fontainebleau by Jean-Léon Gérôme (Château de Fontainebleau)
This outtake from the Siamese reception picture by Gérôme shows the Empress Eugénie and her Ladies-in-Waiting dressed in white evening dresses.
Outtake Photo credit - Daniel Arnaudet.