From Wikipedia

History Of Impressionism
Lecture Eight

Paris Under Siege

 Artists' petitions requesting a new Salon des Refusés in 1867, and again in 1872, were denied. In the latter part of 1873, Monet, Renoir, Pissarro, and Sisley organized the Société Anonyme Coopérative des Artistes Peintres, Sculpteurs, Graveurs ("Cooperative and Anonymous Association of Painters, Sculptors, and Engravers") for the purpose of exhibiting their artworks independently. Members of the association, which soon included Cézanne, Berthe Morisot, and Edgar Degas, were expected to forswear participation in the Salon. The organizers invited a number of other progressive artists to join them in their inaugural exhibition, including the older Eugène Boudin, whose example had first persuaded Monet to take up plein air painting years before. Another painter who greatly influenced Monet and his friends, Johan Jongkind, declined to participate, as did Manet. In total, thirty artists participated in their first exhibition, held in April 1874 at the studio of the photographer Nadar.