During the War, fashion began to simplify, as Poiret's Ballets Russes dresses disappeared with his induction into the army and as their extravagant decorations began to seem inappropriate. A sober, even retrograde, mood prevailed. In the face of wartime shortages, Chanel's practical, albeit expensive, jerseys seemed an instant modern classic, appealing to wealthy clients because, in the words of historian Valerie Steele, "they made the rich look young and casual."(32) Couturiers like Paul Poiret returned from the War to find that the aristocratic society lauded by the promoters of the San Francisco exposition as "that aristocracy of diplomates [sic]" no longer existed. Russian nobles who had fled to Paris after the Revolution of 1917 were living in penury, having been deprived of their incomes. Once well-to-do Russian women were earning their livelihoods by decorating dresses by Patou and Chanel with the traditional embroidery that they had learned as a female accomplishment in their former lives. Balkan and Eastern European monarchies had disappeared altogether. Many French and English aristocrats had been killed in the great battles of World War I, and the postwar cycles of depression and inflation created instability and financial uncertainty.

When Paris did revive, it awoke to a younger society with a different style and an American tinge. The spacious stage setting that had been Paul Poiret's Paris in the Belle Epoque once again served fashion, as the newly wealthy installed themselves in the Hotel Ritz and patronized cafés like the avant-garde Le Boeuf sur le Toit or Le Jardin de Ma Soeur, the nightclub that Elsa Maxwell created for couturier Edward Molyneux. Artists and designers, resuming their quest for an overarching French style, found it in the coalescing of what was then referred to as the "moderne" (renamed "Art Deco" long after the Exposition des Arts Décoratifs et Industriels Modernes of 1925, which was the source of the name). Technological innovations had changed life physically as well: the electric light, the radio, the motion picture, the automobile all came into common use. Life accelerated. Everything was in motion. Women drove cars, went out to work, played tennis and golf, and learned ballroom dancing. Some agitated for the vote and for complete equality with men. In Providence after 1920, when women were granted the franchise, Tirocchi client Harriet Sprague Watson Lewis found it important to record in her "Line A Day" diary each time that she went out to vote.

Clothing changed with women's evolving roles in modern society, particularly with the idea of increased freedom for women. Although society matrons of a certain age continued to wear conservative garments, forward-looking and younger women now made sportswear their dress of choice. The formal mood of the pre-War world was giving way to a more casual approach. The tubular dress of Paul Poiret had metamorphosed into a similar but shorter silhouette with pleated, gathered, or slit skirts, making ease of motion the rule in women's fashion for the first time in its history.

If Anne Hollander is correct, however, there is much more to be said about the emergence of the 1920s chemise, which, topped with the cloche hat, became the uniform of the early to middle years of the decade. Hollander maintains in Seeing Through Clothes that "developments in fashion are like changes in pictorial art; in clothes, as in pictures, technical inventions and social change are secondary to visual style." According to Hollander, garments on the body please not so much because they serve specific uses or circumstances (although they do), but rather because they resemble "a current pictorial ideal of shape, line, trim, texture, and motion."(33) Developments in art and fashion during the years from 1906 onward had accustomed the modern eye to the abstract by the early 1920s. The challenges that cubism presented in the Armory Show of 1913 in New York had now been assimilated. The tubular, slim silhouette proposed by Poiret, Fortuny, and Vionnet had now become the norm. The cylindrical silhouette of the body and the ovoid of the head accented by close-cropped hair and cloche hat are the geometries of Picasso, Léger, Duchamp-Villon, and others throughout the first two decades of the twentieth century [figs. 108-109; compare fig. 104, p. 144, and fig. 128, p. 161].

When the long-awaited Exposition des Arts Décoratifs et Industriels Modernes finally did occur in 1925, instead of introducing "moderne" fashion, it simply confirmed what Tirocchi clients had already accepted. The Exposition had been conceived some years before World War I as a way to renew French domination of the decorative-arts industries. It was postponed because of the War; and had to be put off further due to the straitened circumstances of the French government and postwar scarcity and economic depression. Finally, the exhibition opened in the various national and international pavilions that occupied the area from the Grand Palais to the Invalides, including the banks of the Seine. After the War, the economic need was even greater than in 1913 to reestablish the French luxury industries, and the Exposition emphasized opulence at the expense of modest but well designed decorative arts that could be produced industrially.