“Bals des victimes” were given by Incroyables…

… the young “Merveilleuse et Incroyables” gave lavish balls and parties for the public.  They greeted each other doing violent movements of the head as if it was being decapitated, & danced in mourning dress, or wore black armbands.

A ball held at the Hotel Thellusson in Paris,  restricted the guest list to the grown children of those who had been guillotined.

(sketch: typical dress to go to “le bal des victimes”.  Note the significant red detail which was common on the women representing dripping blood, and the high collars and cravats on the men to “hide their necks”)