Short answers, pulled from the story.
The petticoat served as a structural necessity to create volume and prevent skirts from collapsing into shapeless drapes. It was engineered to form a bell shape using multiple layers of cotton, silk, or tulle hidden beneath the outer dress.
The word petticoat derived from Middle English terms in the 14th century and was originally designed to be seen as a small coat. Both men and women wore these padded or quilted undercoats for warmth from the mid-15th century until the 17th century.
During the mid-19th century, petticoats were worn over hoops known as crinolines to create the iconic bell shape of the 1860s. By the 1870s, they developed flounces toward the back to accommodate the bustle, and colored silk petticoats with decorative frills became fashionable by the 1890s.
Designer Sybil Connolly observed a Connemara woman wearing a traditional red flannel petticoat and purchased fabric from a local shop to create a quilted evening skirt. This garment became a huge success at a fashion show in New York in 1953 and is now part of the collection at The Hunt Museum.
South Asian petticoats are rarely shorter than ankle length and are always worn from the waist down, often called inner skirts or inskirts. In Japan, a similar garment known as a nagajuban is worn under the kimono and typically resembles a shorter kimono made of white or historically red silk.
The phrase petticoat government referred to women running government or domestic affairs and appeared in an Irish pamphlet published in 1780 and Washington Irving's Rip Van Winkle in 1819. It also inspired novels by Frances Trollope in 1850 and Emma Orczy in 1911, while the phrase petticoat affair described a scandal during President Andrew Jackson's administration.