The notion of “Union Sacrée” against Germany invoked by the French President Raymond Poincaré, August 4, 1914, reflects on art, because the war is also conducted on the cultural front. The journal La Musique pendant la guerre, whose editor-in-chief is the musician Francis Casadesus, is very close to the government, and, more precisely, enjoys the protection of Albert Dalimier, head of cultural war propaganda, who is heavily invested in helping musicians. The motto of La Musique pendant la guerre could be stated in these terms: patriotic music. The aesthetic project of the journal, devoted to “the movement of musical art”, is unquestionably French and unifying. Indeed, the mission is to focus on the movement of French musical art, to contain the interruption of French musical life and art in war and accelerate the revaluation of French music on a larger scale, temporal and spatial. We will show in this article that the offensive musical patriotism dictated by the circumstances is in fact linked to a more entrenched nationalist conception. Clearly argued, it has a program of action. First of all, we will see that this one is used to give back to French music, on the occasion of the war, its rights of promotion and diffusion considered as flouted for 40 years. It is a collective discourse with a structural content and not only a cyclical and isolated claim that would emanate from a minority of the Action française maurrassienne. Secondly, this program is committed to maintaining this state after the conflict and lays the foundation for a post-war aesthetic debate.