The years that followed the return of Alsace and Lorraine to France after World War I proved that reunion was a complicated and painful process. The potential for misunderstanding, if not outright conflict, between Alsatians and French policy-makers was from the outset grossly underestimated by virtually everyone on both sides. Alsatians saw no incompatibility between the wish to preserve their regional cultural personality, or particularism, and their loyalty to France. The believers in the ‘Republic one and indivisible’, however, did. The preservation of Alsatian particularism, especially in language and religion, was regarded by French politicians as the perpetuation of German cultural and political influence. The end of the armistice celebrations and the introduction of a transitional administration brought the realisation that the cultural gulf between France and Alsace, widened by years of separation following the Treaty of Frankfurt of 1871, could not be legislated away. With few exceptions, the people on both sides of the Rhine who welcomed the end of the annexation had assumed that the commitment to reunion was sufficient to make it a success.1 This belief was nowhere more rapidly disproven than in the matter of religion. The enforcement of French legislation ending the role of the state in overseeing the congregations became the flash-point between the Catholic majority in Alsace and the Third Republic.