Debussy was an important figurehead for the avant-garde of 1913. Although he kept his distance from the Société Musicale Indépendante (SMI), maintaining his involvement with the Société nationale, his works were regularly performed at the SMI's concerts. Debussy's opera Pelléas et Mélisande had been a unifying inspiration for the group ‘les Apaches, which centred on Ravel and included one of Debussy's most vociferous spokesmen, Emile Vuillermoz. The period from 1913 to 1920 saw Debussy's appeal spread from this relatively small group of experimental enthusiasts to the musical mainstream. An important factor in this process was the role Debussy and his spokesmen played in arguing that his innovations, which clearly drew on a range of sources from numerous national traditions, were in fact French. This process of persuasion by means of the press had begun after the shocking premiere of Pelléas, which had initially confounded audiences, particularly in its novel treatment of the voice and understated approach to orchestral and dramatic expression. Louis Laloy emerged as a principal interpreter of Debussy's work: he argued that the opera was linked to the distant past; that Debussy's declamation was both French and natural; and that Pelléas represented a long awaited alternative to French Wagnerism. Although Debussy's interest in the French musical past emerged in his critical writings from 1903, he became increasingly vocal during World War I in displaying his patriotism through his public statements and his compositions.