The two principal head bishops, or primates, who steered twentieth-century Poland's Catholic Church—August Hlond (in office 1926–1948) and Stefan Wyszyński (in office 1948–1981)—both had deep ties to the territory that, following the Third Reich's September 1939 invasion of Poland, would be annexed to Germany as the Reichsgau Wartheland (also called the Warthegau). Hlond served for two decades as Archbishop of Poznań and of Gniezno, the proverbial cradle of Polish nationhood; Wyszyński was trained and long affiliated with the seminary in Włocławek, the intellectual beating heart of the prewar Polish clergy. Four years into the war, Hlond was under house arrest in France, while Wyszyński was in hiding in the forests north of Warsaw. At the same time, in both Poznań and Włocławek, auxiliary bishops had been targeted for repression: by the start of 1943, the Poznań suffragan Walenty Dymek expected to be deported to Dachau, while the Włocławek auxiliary Michał Kozal was already there. Dymek, fated to remain under house arrest, would be spared deportation; Kozal, after enduring three years of abuse and forced labor, perished at Dachau, reportedly the victim of a lethal injection.Theirs is the world painted in painstaking, sometimes gruesome, sometimes awe-inspiring detail in Jonathan Huener's The Polish Catholic Church under German Occupation: The Reichsgau Wartheland, 1939–1945. The subtitle must not be overlooked, as one of the central premises of this work is that the “Incorporated Eastern Territories” taken from Poland by the Third Reich have gotten far less attention than they deserve in a historiography focused largely on the General Government. Huener argues forcefully that, as bad as things were for Polish Catholics in Kraków or in Warsaw, “treatment of the Catholic Church was more brutal in the Warthegau than anywhere else in German-occupied Poland or German-occupied Europe” (p. 5).Covering the regions of Łódź and Inowrocław in addition to Poznań and Włocławek, the Warthegau took its name from the Warta River. Following its incorporation into the Reich, this Gau became Germany's second-largest, with a 1939 population of approximately 4.9 million—of whom 85 percent were Poles. Some of its lands had belonged to the Russian partition of Poland before 1918, others—to Prussia, and then Germany. What unified these territories was the dominant position of the Roman Catholic Church at the center of cultural, social, intellectual, and political life.For this reason, Huener argues, these lands’ incorporation into the Reich triggered a frontal assault on the Polish Church. (The author relies heavily—at times, a bit tediously—on the German terminology, i.e., a Kirchenpolitik of “secularization” was inseparable from a Volkstumspolitik of “Germanization.”) Huener deliberately combines the national with the confessional here, arguing that National Socialism's henchmen—especially the infamous Gauleiter/Reichsstatthalter Arthur Greiser, who governed the Warthegau throughout the war with an iron fist and with considerable latitude from Berlin—were guided by the axiom that “the Polish church is always in the service of Polish hatred” (p. 51). As a result, the Germans sought to shut down Polish Catholicism (German and Volksdeutsche Catholics enjoyed considerably more freedom in their religious practice) through a mixture of mass murder, terror, forced labor, property seizure, and a dramatic reconfiguration of the religious geography of the region. By the fall of 1941, for example, of the thirty churches and forty-seven chapels that had operated in Poznań at the time of the German invasion, only two churches and one chapel remained accessible, for a population of 230,000 Polish Catholics. Two-thirds of the Warthegau's male clergy and one-fourth of its women religious were incarcerated in camps and prisons; churches were shuttered and repurposed in ways often explicitly calculated to profane the sacred space. By the end of 1941, Greiser's administration had leased the crypt of the Łódź cathedral for the cultivation of mushrooms.The Polish Catholic Church under German Occupation is a masterpiece of “thick description.” Simply put, this is one of the best-researched books that I've ever encountered. Huener has mined not only German and Polish state archives, Polish émigré collections, and documentation held by Yad Vashem and by the US Holocaust Memorial Museum, but he has clearly traveled to all of the sites whose wartime fates he reconstructs in the book, and he has scavenged and read everywhere he could, from convents and seminaries to postwar collections of interviews gathered by Church officials and communists alike. Huener is also an elegant and eminently readable prose stylist. His book seamlessly interweaves rich portraits of individual and collective human suffering and heroism (without crossing over into martyrology), with some helpful and informative number-crunching, as well as cool-headed and insightful analysis of various institutional logics and ideological ambiguities. Huener thereby sheds light on both the Third Reich's administration and on various levels and domains of the Catholic Church, from local convents up to the Holy See. Especially rich are the portraits of what might be called sites of martyrdom—the sadistically run Fort VII prison in Poznań, the economically driven yet hopelessly unprofitable Nonnenlager at Bojanowo, and of course the infamous Dachau camp—as well as biographies of Polish (and German) clergy and National Socialist brass alike. The book offers systematic and well-organized prosopographic insight alongside comprehensive and well-edited footnotes and bibliography. Author and press alike are to be congratulated on the treasure trove of valuable and illuminating archival photographs reproduced within the book.The book's structure is unusual: eighteen brief chapters, each built around a thematic or conceptual conceit (in most cases, a “keyword” from the German or Polish) rather than chronological narrative. For the most part, this thematization works very well, and several of the chapters—particularly chapter 3 (Hetzkaplan, or “agitator priest”), chapter 8 (Profanacja, or “desecration and plunder”), and chapter 13 (Nonnenlager, on the Bojanowo work camp for nuns)—will make for ready and, indeed, essential teaching material in undergraduate and graduate study alike. But the chapters differ substantially from one another in length, tone, and subject matter. Some are rich empirical chronicles, others—conceptually and historiographically driven analytical essays. The overall architecture of the book really comes into focus only in chapter 4, and even then, the shifting timelines from one chapter to the next remain a source of confusion. Although many chapters jump back and forth in time across the five years of German occupation, only chapters 14 and 18 really focus on 1942–1944, while the rest of the book is squarely planted within the first two years of the war. Some chapters confusingly cross-reference much earlier chapters in the book, with the result that the conscientious reader needs to keep flipping back and forth.Readers knowledgeable about Catholic history may get the feeling that the author has dramatically undersold the book's heuristic implications. Huener engages many historiographies, but as his introduction makes clear, this is fundamentally intended as a contribution to “a wider, comparative, ‘European’ historiography that examines the motives and experiences of German occupation” (p. 8). Regrettably missing, however, is much of the new historiography of transnational Catholicism that now occupies pride of place in modern European historical scholarship. Especially relevant here is Giuliana Chamedes's book A Twentieth-Century Crusade, given her seminal reframing of mid-century mainstream Catholic internationalism as fundamentally nationalist (in other words, dovetailing quite well with many assumptions coming out of Berlin, if not Arthur Greiser's own Gau headquarters).1At the end of the book, one of its key guiding questions—could the “Polish Catholic” be separated from the Roman Catholic?—remains unresolved. I spent much of the book (especially beginning with chapter 5, where Huener emphasizes that Greiser and his Berlin superiors alike saw the Holy See's 1925 concordat with Poland as null and void) waiting for the infamous 1933 Reichskonkordat to be addressed, only to encounter a breezy note in the book's penultimate chapter that the Third Reich “had, since 1940, proceeded from the assumption that the incorporated territories were not subject to the terms of the 1933 concordat between the Nazi state and the Vatican, and its rejection of Vatican diplomatic efforts was formalized in June 1942” (p. 281).Such a summary dismissal of the matter is a mistake, as the question of concordats was no mere legal curiosity, but instead cut to the very heart of whether the Nazis succeeded in decoupling Polish Catholics in the Warthegau from the Roman Church. The motive force behind Pope Pius XII's wartime strategy (flawed, tragic, and inhumane that it was) was the assumption that prospects of future diplomatic victories (however tenuous) justified passing in silence over mass repression and ethnic cleansing, including—in the case of Huener's story—the near-extermination of the male religious of west-central Poland. Given the rich and nuanced historiography of the Reichskonkordat, this subject deserved more serious treatment—not least because it profoundly impacts the assumptions guiding how Huener tells his story. If the Reichskonkordat did not apply to the Warthegau, then this is tantamount to the Holy See tacitly accepting the de-Catholicization—indeed, the complete secularization, just as Greiser wished it—of Polish Catholicism in the territory. That, in turn, importantly reframes the question of what Warthegau Polish Catholics believed they were doing. The absence of canon law considerations in this book becomes especially confusing in light of Huener's fascinating reconstruction of the (quasi-)dissident activities of the Poznań apostolic administrator for German Catholics, Hilarius Breitinger, whom Huener rightly lauds for defying Greiser's insistence on absolute segregation of German Catholics from Polish Catholics. After all, if neither the 1925 Polish concordat nor the 1933 Reichskonkordat applied in the Warthegau, then where was the canon-law basis for Breitinger's pastoral care over Poznań Germans?Powerful though this book is, the author would have done well to step back in its final pages and reflect on how the suffering and repression of Polish Catholics in the Warthegau speaks to broader debates about “secularization”—whether reflecting on National Socialism as a political religion, or nationalism's role more generally as a force of secularization in twentieth-century Europe, or how the Warthegau story can be read as pushing back against long-standing interpretations of secularization as a mere “subtraction story” (to borrow from philosopher Charles Taylor). In so doing, Huener regrettably circumscribes the implications of his own analysis, imposing a horizon line that hews very close to the archival material and remains oriented toward the nation-state historiographies of twentieth-century Germany and Poland. Given Huener's extraordinary research and important conclusions, The Polish Catholic Church under German Occupation could have had much wider scholarly resonance inside and outside the historical profession. Instead, it reads more modestly, as a plea for Germanists and Polonists alike to take the Warthegau story seriously as a portal to understanding National Socialist ideology and colonial policy.But in the end, was it? Huener himself is clearly of two minds. He calls the Wartheland “a testing ground for policies to be implemented in a victorious Reich after the war” (p. 66), all while cautioning that it “would not be appropriate to regard measures against the churches in the Wartheland as a ‘blueprint’” (p. 69). In the end, the reader wonders: was the Warthegau the beginning of a new Nazi model of secularization for the world? Or was it merely a hell of Arthur Greiser's making?