The young visionary gallerist decided to support and promote this new art movement by informing foreign art journals about the production of the artists he was advocating. "I didn't have the slightest doubt about the aesthetic value of these pieces nor about their importance in the evolution of painting, because although I did not know about the painting business, I did know about painting."[1] Kahnweiler would take photographs of the pieces by the artists from his gallery, which was unusual at the time. He was thus able to promote the work, convey its importance, and gather information of great value for understanding the output of that period.
Many exchanges and letters between Braque, Picasso, and Kahnweiler reveal both the trust that developed between the three of them and the creative effervescence and closeness shared by the two artists: "My dear friend, it has been several days since I last wrote to you, but Braque and I have been going on so many walks together and having so many discussions about art that time just slipped by […]."[2] The gallerist was kept abreast of the two friends' pursuits in Sorgues, where Picasso had taken refuge with Eva, his new love, and of Braque's first collages, which brought on major changes in Picasso's work.
A contract sealing an agreement between Picasso and the gallery was signed in 1912. In 1913, Kahnweiler also took on Juan Gris, Maurice de Vlaminck, and Fernand Léger. The artists focused on their work, committing to deliver pieces on a regular basis; the gallerist, in turn, provided them with regular monthly payments that brought them considerable material comfort.
Kahnweiler organized international exhibitions in Berlin, London, and Amsterdam, among other places, and ensured sales through a network of foreign collectors. He pursued an exclusive and efficient "international marketing" effort, strategically placing Cubist works by Picasso, Braque, Gris, and Léger in avant-garde exhibitions ranging from Heinrich Thannhauser's Moderne Galerie in Munich to the Washington Square Gallery run by Michael Brenner —all of which, paradoxically, was easier to do abroad than in France.
[1] Quoted by Yve-Alain BOIS, "Kahnweiler Daniel-Henry - (1884-1979)", Encyclopædia Universalis [online], URL : http://www.universalis-edu.com/encyclopedie/daniel-henry-kahnweiler/
[2] Letter from Picasso to Kahnweiler, Sorgues, Sunday, August 11, 1912. Published in Pierre Daix, Dictionnaire Picasso, Éditions Robert Laffont, 1995.