Throughout his career as a researcher and professor, Stefan Samerski has written numerous works on Catholic Church-State relations in central and eastern Europe. In Germany and the Holy See, he draws extensively from his oeuvre to produce an accessible narrative that offers a chronological examination of diplomatic relations between the two entities. In his study Samerski seeks to understand ‘how effectively the Holy See and Germany worked together in the first half of the twentieth century and pursued common foreign policy interests’ (p. 7). This cooperative relationship was generally fruitful until National Socialism forced its disintegration. For Samerski, there is a void in such a study in relation to its historiography. He believes that the opening of the Pius xi papers by the Vatican necessitates a careful re-examination of German-Vatican relations over a broader period. By contrast, he does not expect to discover anything startling novel among the newly opened papers of Pius xii's pontificate and therefore completed his work before having an opportunity to consult them. Instead, he argues that the Vatican's eleven-volume opus, Actes et documents du Saint-Siège relatifs à la Seconde Guerre mondiale (1965–81), already contains the most relevant documents. However, interesting enough, his citations reveal almost no consultation of them.

After a brief overview of German-Holy See relations before 1918, Samerski divides his study into three parts: the Weimar Republic, Papal Diplomacy and the Third Reich, and the Second World War. Critical to all three periods were two people: Eugenio Pacelli, first as the papal nuncio to Bavaria (1917–20), later as nuncio to Germany (1920–9), then as Cardinal Secretary of State (1930–9) and finally as pope (1939–58), and Diego von Bergen, German ambassador to the Holy See (1920–43). Both Pacelli and von Bergen play prominent roles in the study. At the same time, Samerski provides little new insight on von Bergen to counteract his claim that the German diplomat's ‘work has not yet been fully appreciated’ (p. 7). Samerski does take many opportunities to point out Pacelli's diplomatic gifts. Upon his arrival in Germany before the end of World War I, the German-speaking Pacelli was quick to comprehend Bavarian provincialism. He also created intelligence networks in Munich and Berlin, even though, at first, he had a challenging time adjusting to the industrial-secular character of the German capital. Yet Pacelli did not succeed solely on his own. Individuals such as Julius Graf Zech von Burkersroda, Prussian minister at Munich, and Matthias Erzberger, an influential Catholic Centre Party politician and Reich Finance Minister (1919–20), offered Pacelli useful introductions. The Centre Party priest-politician and chair (1928–33), Ludwig Kaas, also performed a similar role for Pacelli, especially after the latter's move to Berlin in 1925.

Samerski's account details much about the evolution of the diplomatic staff, both in the German embassy at the Holy See and the Berlin nunciature. He introduces several forgotten but influential figures in Vatican-German relations, such as Monsignor Dr Johannes Steinmann, Breslau's former cathedral dean, and spiritual consultant at the German Vatican embassy; Richard Delbrueck, archaeologist, former director of the German Archaeological Institute in Rome and Foreign Office assistant assigned to German-Vatican relations; and Father Eduard Gehrmann, a priest of the Society of the Divine Word, a Russian expert and privy secretary in the Berlin nunciature (1925–45). Indicative of his many secondary source selections, Samerski relies on Hans Preuschoff's 1984 uncritical biography of Gehrmann while completely ignoring his pro-National Socialist outlook.

The outcome of the First World War provided an opportunity for German-Vatican relations to evolve positively. Pacelli recognised Germany's ostracisation from other nations and the public perception within the budding Weimar Republic that the Versailles treaty needed revising. Repeatedly, the Holy See advocated on behalf of Germany. In Danzig and Upper Silesia it promoted apostolic administrator candidates sympathetic to German concerns. During the Ruhr crisis, it negotiated for German interests and intervened to reduce the severe sentencing of the business magnate, Gustav Krupp von Bohlen und Halbach. At times, such interventions backfired as in the case of the June 1923 bombing of the Duisburg-Hochfeld Railway Bridge when the Holy See's public comments appeared to condemn German resistance to foreign occupation in the Ruhr region. The Holy See made amends by supporting Germany's entry into the League of Nations.

For its part, Germany supported Vatican interests in Soviet Russia after the Bolshevik leadership implemented harsh measures against religious institutions. Samerski speaks of an ‘unholy alliance’ that was briefly formed when Germany brought Soviet and Vatican diplomats together at the 1922 World Economic Conference in Genoa. Despite valiant diplomatic and charitable efforts by the Vatican, it was evident by the mid-1920s that Soviet anti-Church policies were permanent. By 1930 Pope Pius xi made it public that the Vatican stood in opposition to Bolshevism.

Samerski's account of relations under National Socialism and during the Second World War reveals little that is new. It leans heavily on the work of Gerhard Besier, Hubert Wolf, Manfred Clauss, Pierre Blet and Thomas Brechenmacher. A similar critique might be made of the section on the Weimar Republic. Samerski very closely echoes the arguments of Stewart A. Stehlin and Hansjakob Stehle, citing their works repeatedly. Throughout, Samerski supplements his presentation with quotations from documents primarily drawn from the archive of the German Foreign Office.

Following the publication of the 1937 papal encyclical Mit brennender Sorge, the Vatican lost most of the remaining influence that it had with the German government. With the onset of the Second World War and the German occupation of conquered territory, any existing concordats were ignored. The German government also refused to extend the tenets of the Reich-Vatican concordat to its annexed and occupied territories. Nuncio Cesare Orsenigo had to rely on the generosity of his contacts in various Reich ministries for favours and information, especially on the plight of Catholics in occupied countries.

Samerski provides little insight into Vatican-German diplomacy and the plight of European Jews. To be fair, this topic is extensive and requires a separate monograph. Nevertheless, when he does address it, he is far too magnanimous in his assessment of the Holy See's intervention in behalf of Jews. In general, his bibliography is limited and selective. He has also mostly ignored English-language secondary works. What he has done, however, is to author a study that will primarily benefit individuals who have little knowledge of Vatican-German diplomatic relations during this period.