Dress in The French Revolution, Empire and Romantic Periods
This time frame from 1789-1825 is actually several different sub-periods. The first, 1789-1799, the period of The French Revolution, is a sharp transition period. The second 1800-1815 is the time of the French Consulate and Empire, and is a stable Neo-classical period. 1815-1825 is the late Neo-classical period that shows a gradual shift towards the Romantic style.
Dress in The French Revolution

Dress during this period goes through a massive shift. Late 18th Century women's dress collapses from it's padded and puffed look to a thin, often translucent silhouette. As the French Revolution progressed, different women's styles were adopted that appeared to have reference to the revolutionary politics, social structure and philosophy of the time. In the early 1790's, for example, the "English" or man-tailored style was favored as it hinted towards the leanings of constitutional monarchy. There was a brief fashion for plain dresses in dark colors during the Terror of 1792, but when the Directory took over French fashion again went wild, trying out "Rousseauesque" fashions in "Greek", "Roman", "Sauvage" and "Otaheti" (Tahitian) styles.
Dress a'la Greque (Hoey)
The Psudo-"Greek" look proved most popular and was adopted as the standard style in Europe in the late 1790's

While Men's Costume in the 1790's also becomes thinner in line, it separates it's style from women's dress by beginning to lose nearly all forms of surface decoration, lace and bright color, as "irrational" and feminine effluvia. This change is slow, but it completely alters men's dress by the mid 19th Century into dull dark uniform dress.
Other major changes include the adoption of trousers from the dress of sailors and the urban proletariat of the French Revolution, the passing of the fashions for wigs and hair powder, and the (very temporary) demise of the corset.
The bonnet is invented as a hat that is meant to look like a Greek helmet, but it quickly is altered in style out of all resemblance to the original.
Bonnets from "Wiener Zeitschrift", Vienna, 1820 in Max von Boehn's Modes and Manners of the 19th Century
The Neoclassical Period 1800-1825
Probably due to post Revolutionary backlash against female influence in politics, later reinforced by the German Philosopher Schopenhauer (who promoted the view that men were supposed to be rational and women emotional), the sexual dichotomy in dress becomes more pronounced in this era, a trend which continues through the 19th Century. The direction of fashions towards Neo Classic dress for women, and increasingly drab utilitarian dress on men, continue in a steady manner in this very stylistically stable period.
1807
1809
Women's dress locks into a pattern of light colored muslin gowns, high waisted with little puffed sleeves, and psudo-Greek hairstyles, which achieved an apex at the coronation of the Emperor Napoléon in 1804.
Napoleon's sisters at his coronation.
As the period proceeds, the originally simple lines of these gowns are increasingly decorated with ruffles and puffs, the skirts get puffed out with petticoats, the waist lowers and tightens with corsets, until by 1825 it is hard to see how the style worn was ever imagined to look Greek.
1822 Vienna from Max von Boehn's Das Beiwerk der Mode, 1928

Men's dress also keeps on a fairly steady course towards increasing dullness. Fashion magazines continue to push men's dress towards foppish extremes, but men who actually count in the fashionable world tend to push for plainer styles. Beau Brummell, the leader of male sartorial fashion in England in this period was noted for wearing only black with a white shirt for formal evening wear, a marked departure from the style of the previous century. Tubular and fitted trousers also move from a radical fashion statement to everyday wear for most men of the upper classes.
Clothing from 1825-1850 The "Romantic" Period
The trend towards sexual dimorphism in dress reaches an absurd apex in this period. Men's fashion becomes a series of undecorated black tubes, like the smoke stacks of the The Industrial Revolution (an analogy they were even conscious of at the time), while women's dress continues to balloon out with ruffles, decorations and petticoats until women look like ambulatory wedding cakes.
Fashion Plates from Le Folliet c.1839-1840
Both men's and women's dress becomes more complex during this era due to the invention of the Sewing Machine, and the popular dissemination of pattern books and systems for garment cutting. Men's clothing construction, while outwardly simple, begins to acquire the internal padding, interfacings and complex structure that makes modern men's suits fall so smoothly even over an object as lumpy and mobile as the human form.
early Hand crank sewing machine
Elias Howe, the inventor of the first mass produced, practical sewing machine, originally demonstrated it's utility to a group of prospective investors by holding a sewing race between himself and his machine, and ten professional hand stitchers. He easily won, and the economic situation of stitchers (mostly female) declined as a consequence of the adoption of the invention. With a sewing machine, a stitcher could produce ten times the output as before, with greater quality, but the stitcher rarely could afford the machine, and with so many stitchers out of work, stitchers were easily replaceable. Industrialists would invest in the machines, hire the stitchers cheaply, and then swallow the profits that their increased output produced. With profits so high, soon competition between manufacturers of clothes got fierce, and so producers tried to "improve" their product by adding more sewing decoration, such as ruffles, pleats, and top stitching, to lure customers. The end result was that fashionable Women's dress became incredibly over decorated in the 19th Century.
Another result of this increased output in clothing manufacture was that poor people's clothing got better, and the rags of earlier eras were replaced by cheaply made mass manufactured work clothes. The middle classes were able to afford more than clean simple clothes, and began to actively indulge in fashion for it's own sake.
"The Last of England" by Ford Maddox Brown, showing the dress of poor English people as they emigrate to Australia.
Fashionable women's dress grew more and more cumbersome and impractical during the 1830's and 1840's. The visual line of 1840's gowns, hats and headdress all point down, and the eyes of women depicted in fashion plates are demurely cast to the floor. The increasing size of the skirts, held out only with voluminous and usually unsanitary crinoline (horsehair canvas) petticoats, made the weight of the skirts oppressive, and movement awkward. Tight laced Corsets of a waist-cinching style, pinched the waist without providing the back supporting properties of corsets of other eras.
This is the time of the tortured and victimized Bronte heroines, not to mention the tortured and victimized Bronte Sisters themselves. The 1840's proved such a low point for women in Western history, that the worm finally turned, and women began to organize and agitate for the vote, dress reform, and the right to enter schools and professions closed to them.