Nationalism has been the subject of numerous studies and analysis. It has its authorized historians (Raoul Girardet, Michel Winock, Zeev Sternhell...) and its leading figures (Boulanger, Déroulède, Le Pen...). Should we fear being redundant if we venture into this field of research ? It seems to us that the prism through which we are accustomed to address the issue for the 1870-1950 period (universalist republican nationalism or hard-line conservative nationalism) does not sufficiently take into account the existence – more widespread than what is believed- of an ardent patriotism that, without being extreme, remains fundamentally republican and at the same time conservative. The religious art historian, Émile Mâle, appears to us an emblematic figure of this thinking.