Which art dealer exhibited Cubist works at the Galerie de l'Effort Moderne?

Léonce Rosenberg exhibited Cubist works at the Galerie de l'Effort Moderne.

Rosenberg was a Parisian art dealer, collector, writer and publisher who became an important supporter of Cubism during and after the First World War. In early 1918, he renamed his gallery the Galerie de L'Effort Moderne and redirected it toward avant-garde art, especially Cubist painting and sculpture.

The gallery presented a succession of exhibitions by leading modern artists. Auguste Herbin opened the program in 1918, followed by artists including Henri Laurens, Jean Metzinger, Fernand Léger, Georges Braque, Juan Gris, Gino Severini and Pablo Picasso. Rosenberg also used publishing, lectures and musical events to promote the intellectual case for Cubism.

The alternatives are associated with Cubism but played different roles. Daniel-Henry Kahnweiler was an earlier and highly influential dealer of Picasso, Braque and other Cubists; Ambroise Vollard and Paul Guillaume were also major Paris art dealers. The specific gallery named in the question, however, belongs to Léonce Rosenberg.