The most famous fancy dress party of the 1910s was held in Paris by the legendary designer Paul Poiret of the night June 24, 1911. Called “The Thousand and Second Night” and themed on One Thousand and One Nights, costumes were not only encouraged, but required. If guest arrived un-costumed, or Poiret determined their costumes did not fully support the party’s theme, they could choose to don a costume designed by Poiret or were asked to leave.
Most of the women’s costumes Poiret designed for the event, including the one pictured, featured scandalous harem pants, something that would influence mainstream fashion to introduce the hobble skirt soon afterward.

