Historians have long believed that Catholics were late and ambivalent supporters of the German nation. Rebecca Ayako Bennette's bold new interpretation demonstrates definitively that from the beginning in 1871, when Wilhelm I was proclaimed Kaiser of a unified Germany, Catholics were actively promoting a German national identity for the new Reich.

In the years following unification, Germany was embroiled in a struggle to define the new nation. Otto von Bismarck and his allies looked to establish Germany as a modern nation through emphasis on Protestantism and military prowess. Many...