"Les Six" (le sis) is a name given to a group of six composers, five of them French and one Swiss, who lived and worked in Montparnasse. The name has its origins in two 1920 articles by critic Henri Collet in Comœdia (see Bibliography). Their music is often seen as a neoclassic reaction against both the musical style of Richard Wagner and the impressionist music of Claude Debussy and Maurice Ravel.
The members were Georges Auric (1899–1983), Louis Durey (1888–1979), Arthur Honegger (1892–1955), Darius Milhaud (1892–1974), Francis Poulenc (1899–1963), and Germaine Tailleferre (1892–1983).
In 1917, when many theatres and concert halls were closed because of World War I, Blaise Cendrars and the painter Moïse Kisling decided to put on concerts at 6 rue Huyghens, the studio of the painter Émile Lejeune (1885–1964). For the first of these events, the walls of the studio were decorated with canvases by Picasso, Matisse, Léger, Modigliani, and others. Music by Erik Satie, Honegger, Auric, and Durey was played. This concert gave Satie the idea of assembling a group of composers around himself to be known as Les nouveaux jeunes, forerunners of Les Six.
According to Milhaud:
[Collet] chose six names absolutely arbitrarily, those of Auric, Durey, Honegger, Poulenc, Tailleferre and me simply because we knew each other and we were pals and appeared on the same musical programmes, no matter if our temperaments and personalities weren't at all the same! Auric and Poulenc followed ideas of Cocteau, Honegger followed German Romanticism, and myself, Mediterranean lyricism!
And according to Poulenc:
The diversity of our music, of our tastes and distastes, precluded any common aesthetic. What could be more different than the music of Honegger and Auric? Milhaud admired Magnard, I did not; neither of us liked Florent Schmitt, whom Honegger respected; Arthur [Honegger] on the other hand had a deep-seated scorn for Satie, whom Auric, Milhaud and I adored.
But, that is only one reading of how the Groupe des Six originated.