Six months before the end of the First World War, in May 1918, Achille Ratti, the future Pope Pius xi, arrived in Warsaw. His mission was to promote conditions for the Church's renewal in a Poland emerging from imperial subjugation to Germany, Russia and Austria-Hungary. Despite his best efforts at mollifying passions and mediating conflicts, he was recalled to Rome three years later, his mission defeated by competing interests in a region wracked by religious, ethnic and national hatreds.

The fourteen essays in this coherent and finely composed volume, which came together following a 2018 conference sponsored by the Institut für Kirchen- und Kulturgeschichte der Deutschen in Ostmittel- und Südosteuropa (IKKDOS), emphasise the problems that Ratti and the Roman Catholic Church faced in the interwar period throughout east-central and south-eastern Europe. These problems – stabilising ecclesiastical boundaries in contested borderlands; satisfying petitions from activists making irreconcilable demands; guaranteeing religious practices for Catholics in lands beset by right- and left-wing secular extremisms; curtailing the political involvement of the clergy; securing pastoral footing amid populations grieving from the losses and resentments of the war – powerfully determined Catholic destinies. The contributors to the volume make this argument by integrating a number of academic trends. These include attention to ethno-religious conflicts and militia violence on the local levels of emergent nation states, the re-centering of the study of religion from structures and institutions to cultures and identities, and the ‘spatial turn’ in historiographical awareness, which in this case forefronts the spiritual implications for the scrambled populations affected by the region's geographic rearrangements.

The analysis unfolds in several zones of ethno-religious-national contact. Chief among these were the Prussian-Polish borderlands between West and East Prussia. Here the conditions of the Versailles settlement led to ecclesiastical chaos. New state boundaries demanded the realignment of dioceses because some parishes fell into unfamiliar jurisdictions amid new populations, all of whom demanded pastoral and liturgical services provided in their mother tongues and according to their unique traditions. A case in point was Memel, which had belonged ecclesiastically to the German diocese of Ermland. Versailles placed it outside German control, and in 1923 it was occupied by Lithuania, but under church law its Catholic parishes still belonged to the diocese of Ermland. Rome had no choice but to reshuffle parishes among the ensemble of jurisdictions now coming into being, which included a wholly new prelature of Memel itself. Diocesan disruptions were even more serious due to the Polish Corridor and the Free City of Danzig. Germans living here demanded, through petitions submitted by pressure groups agitating on their behalf, that they remain part of the diocese of Ermland and thus to their beloved Kulturnation. Poles and the Polish government took exception to the idea. They insisted that residents of the region – Germans and Poles – belonged rightfully to sovereign Poland, with all that this membership implied for the imposition of Polish language and cultural education, including in seminaries. These people also belonged, they continued, not to Ermland, but to the Polish diocese of Chełmno (Culm). Tensions ran so high in this explosive contest of allegiance that Rome, in an act of ‘Solomonic judgment’ (p. 91), detached the region from both Ermland and Chełmno and placed it under an apostolic administrator, who, in 1926, became the first bishop of the new diocese of Danzig. Perhaps the most alarming result of the indignation created by these and other provocations was the erosion of the ‘norm of Catholic universality’ (p. 79), which is to say the splitting up of Catholics by national affinity in an area where national differences among them had been historically honoured. This was a situation the Nazis could exploit. Indeed, by 1933, they enjoyed over 50 per cent support among the Danzig electorate.

The volume examines similar tensions elsewhere. The creation of Czechoslovakia raised concerns about ‘Czechification’ among Germans living in the south-eastern periphery of the old Reich. Accordingly, they demanded inclusion in the predominantly German diocese of Breslau, where they believed their national interests, as well as their Heimat customs of prayer and piety, would be protected and preserved. Czech Catholics, meanwhile, anxious to separate themselves from the humiliating memory of subordination to Austria, preferred ecclesiastical union with Prague, a union that recommended such measures as the territorial expulsion of monks deemed insufficiently loyal to Czech nationalism. Czech nationalism – increasingly secular in its foundations, abrasive in its tone and aggressive in its policies – did nothing to assuage the fears of Germans living along the Bavarian-Czechoslovakian border, who already by the early 1920s demanded Anschluss with Austria to help protect their persecuted coreligionists in the Sudetenland and forfend against the threat of Slavic absorption from the East. Territorial partitions, ecclesiastical realignments, population transfers and national disagreements played decisive roles in the post-war development of Catholic Slovenia as well. Here Slovenes, who lost a third of their historic lands, found themselves in one of two disagreeable situations. Either they belonged to the new kingdom of Serbs, Croats and Slovenes, where the Orthodox Serb majority dashed their hopes for national self-determination and bourgeois secularists attacked the Catholic presence in public life. Or they fell under the heavy hands of Italian occupational authorities in contested border zones, where they faced harassment, intense ‘Italianisation’, incendiary attacks on their church buildings and physical violence by rightist squads. Their complaints received but begrudging sympathy, including in a Roman Curia filled with Italian nationalists and Fascist sympathisers.

These are just some of the accounts of insult, intolerance and betrayal conveyed by this engrossing volume, which represents the study of modern religion at its finest. It coordinates the best traditions of ‘church history’ (Kirchengeschichte) – linguistic facility, intimate command of church archives, deep ecclesiastical knowledge, detailed appreciation of personalities and theological meanings – with the findings of ‘secular’ scholarship in a compelling demonstration of exquisite craft. While the volume features a number of well-chosen images and maps, given the complexity of the topic and the geographic range of inquiry, readers will long for a name and subject index.