This formal gown, with its bold silhouette, is called a sack or sacque in English and a "robe à la française" in French. Although it originated in French informal wear, this style became fashionable in the Western Hemisphere from the 1720s through the 1770s. The aesthetics governing formal dress in this period decreed not only a preference for white fabrics, as seen in this gown, but also a particular form of construction. Two sets of box pleats falling from the back neckband into a wide train characterized the sacque. The loose pleats concealed the fact that the bodice is actually fitted tightly to a corseted body.
The petticoat or skirt was worn over narrow, oval-shaped hoops called paniers. Suspended from the waist, these hoops created a shape that was flat in front and extended as far as two feet on either side of a woman’s body. The oversized, unnatural shape of the petticoat, the sweeping train, and the obvious cost of such a gown symbolized great wealth and privilege, and represented a society so impressed with artificiality that a woman who wore such a dress could not walk naturally.