Historical eras or periods can be confusing. They overlap. They are just slightly different for various categories (i.e., art, music, literature, science and fashion) -- yet sometimes difficult to tell the difference in timeline as things don't always suddenly erupt into being and have evolved from prior efforts and discoveries. Of course there is the human element -- who interprets, who re-visits and researches, who re-writes....lots of ways to confuse readers.
Both the Empire and Regency styles were born out of the formal Neoclassicism that dominated late eighteenth century European art and architecture. Even before the Napoleonic Wars (1799-1815) there was a bitter rivalry between France and England.
In 1804 when Napoleon ascended to the throne as Emperor of France, he implemented an ambitious art and design program as he was determined to make France a leader of fashion as well as an innovator of design and artisan (craft) skills. During the French Revolution (1789-1799) the French textile industry had suffered. Unlike England, use of textile machinery had been non- existent in France. Emperor Napoleon stopped the import of English textiles and he revived the Valenciennes lace industry so that fine fabrics like tulle and batiste could be made there. This was important in the fashion world because both lace and fine fabrics were the main textiles for the emerging high-waisted "Empire" fashion. The "Empire" style was named after the first French Empire of Napoleon Bonaparte (1769-1821; Napoleon I).
"Josephine" - Detail from "Coronation of Napoleon at Notre Dame"
In England, the 1790s-1820s emphasized the elegance and simplicity motivated by the democratic ideas of the French Republic as well as looking back to classical Greece and Rome for fashion inspiration. The direction emphasis, like the Hellenic columns, was vertical. Fabrics were light-weight and often white. Further, a dramatic change from the preceding fashions of multiple layers, heavy fabrics and farthingales emphasizing horizontal lines; ladies often only wore three garments! (Chemise, corset and gown.) The actual Regency Era was a mere nine years (February, 1811 - January, 1820). In late 1810 King George III again became seriously ill. Issues with his mental capacity caused him to be declared incapable of ruling and the Regency Act of 1811 (using precedent of the 1788 Act) was enacted to make his son, George, Prince Regent. Upon George III's death (January 29, 1820), Prince Regent George became King George IV and ruler in his own right. The "Regency" style was named after the George, Prince Regent.
https://www.pinterest.com/pin/242138917436399729/
Recently, while placing these two lovely gowns on exhibit, I was curious about the "Empire" gown versus the "Regency" gown. Unfortunately, as is too often the case, there is very little information from the donors in the files. For example, the striped silk gown (left) was a gift from Mr. Robert Morin (9/1/1999) that included a hand-written not: "Grandmother Pearce's dress at 16 years old." Unfortunately, no other details were provided as to whose grandmother she was, where they resided and a time-frame. The ivory satin wedding gown was a gift from Mrs. Van T. Smith (12/12/1997). The file indicates the garment was "made by an ancestor" of the donor and that the "gown and slippers were in her garage for many years." It would be helpful to have names and dates. (Keep this in mind if you are holding onto family treasures!)
The striped silk gown (left) was professionally crafted based on the structural work and the military -influenced details on the bodice and sleeves. It is, however, missing the "slip" or under-dress.
The ivory satin gown (right ) is known to have been home-made and appears to have been altered by hand and not professionally, to fit someone a little larger than its original wearer. The quality of the stitching is not as fine as the sleeve work, indicating that "piece work" had been purchased. The gown also may have had a sleeveless over-dress.
Another difference is that the silk striped gown has fuller gatherings in the back, while the ivory satin has fewer. The question is, was this ivory satin actually an under-dress, or did the alterations change the fullness of the back of the dress?
For more detailed information on the Empire and Regency eras and fashions:
http://www.wemakehistory.com/Fashion/Regency/RegencyLadies/RegencyLadies.htm
https://janeaustensworld.wordpress.com/social-customs-and-the-regency-world/
https://www.nypl.org/node/5649
http://www.fashion-era.com/regency
http://www.britainexpress.com/History/George_III.htm
https://www.britannica.com/biography/Josephine