Garters encircled the leg, either just above or just below the knee (depends on how your leg is shaped). Description from pinterest.com. I searched for this on bing.com/images
Corset | American | The Metropolitan Museum of Art
A regency cotton petticoat, the trimming on the hem was inspired by the petticoat, c. 1820, The Metropolitan Museum of Art, only the cording was replaced with tucks, because this one is intended under c. 1805 dress
Historically Dressed - Costumes - Underpinnings, c. 1795-1820
scottish plaid clothing | Details about Medieval Scottish Tartan Costume Dress Women Size XL
Wrapped corset, ca 1800, Musee Galliera Lots of interesting information on her site
How to make Half Stays :) scroll down for the English translation.
"Undressing the Regency Lady". Blog post on appropriate undergarments for Regency-period costumes.