John Pollard contends that the period between the election of Benedict xv in 1914 and the death of Pius xii in 1958 can be read as a clearly defined period in the history of the modern papacy. The election of Benedict xv on the eve of the First World War represented a turn away from the anti-modernist campaigns of Pius xi (1846–78) and Pius x (1903–14) which reflected the papal rejection of the values of the modern age. Pollard notes the similarities and continuities in the papal reigns of Benedict xv (1914–22), Pius xi (1922–39) and Pius xii (1939–58) during the subsequent forty-four years. The election of John xxiii in 1958, which led to the convocation of the Second Vatican Council, took the Church and the papacy into different directions from his immediate predecessors.

If anything, the period from 1914 to 1958 was noted for a willingness on the part of the papacy to exist as a player in the modern world and actively to attempt to shape developments in a world which came to be dominated by the totalitarian ideologies and regimes of Fascism, National Socialism and Communism. This approach was foreshadowed by the papacy of Leo xiii (1878–1903), who had argued that the Roman Catholic Church had a responsibility to work with political and social trends of the times; Leo's ideas had influenced many of those who held key Vatican offices after 1914.

Starting from a position of relative international insignificance in 1914, when the Holy See had formal diplomatic relations with only fourteen secular states, the succeeding forty-four years were marked by the establishment of diplomatic relations between the Holy See and an ever increasing number of secular states. This served to make the papacy a more important influence in international relations, especially during the periods of the First and Second World Wars, when it sought not only to find ways to restore peace but also to deliver humanitarian assistance to suffering peoples.

As it was reaching out into the world, the papacy was also working to centralise power within the Church. Started under Pius x and continued under Benedict xv, the codification of canon law was completed in 1917 as a rationalisation of the laws of the Church. This had the effect of confirming that power lay with the papacy and the Vatican officials in the Curia, which itself had been reformed by Benedict xv.

Pollard makes the point that the three papacies between 1914 and 1958 were marked by a continuity of key personnel. Most important was Pietro Gasparri, who served as Secretary of State to both Benedict xv and Pius xi and was responsible for overseeing the codification of canon law, for defining the relationship between the Holy See and secular states in a series of concordats and for working out the vital settlement of the Roman Question with Italy in 1929. Pollard argues that Gasparri was the most important Secretary of State since Cardinal Consalvi at the time of the Napoleonic Wars.

Gasparri was succeeded as Secretary of State in 1930 by Eugenio Pacelli, who had worked with Gasparri on the codification of canon law, had been instrumental in establishing diplomatic relations with Germany during the First World War, had served as nuncio to Germany in the 1920s and, in 1939, was elected pope.

Other continuing figures during this period were Bernardino Nogara, the financial advisor to Pius xi and Pius xii who was responsible for investing the monies received from the Italian Conciliazione; Pietro Tacchi-Venturi, the Jesuit who served as the intermediary between the popes and Mussolini; Wlodimir Ledochowski, long-serving Father-General of the Jesuits; and, in the Secretariat of State, Giovanni Battista Montini, later Pope Paul vi (1965–78) and Domenico Tardini, who became first Secretary of State to John xxiii.

Pollard credits Pius xi with laying a solid foundation for the papacy in the twentieth century by building on the initiatives of his predecessor. In addition to encouraging indigenous mission clergy and exploring possibilities of reunification with the Orthodox Church, Pius xi developed an interest in the model of Italian Catholic Action for inculcating Christian values in secular society and encouraged Churches in other countries to avail themselves of the Italian model.

Pius xii continued to build on Pius xi’s foundation, but proved to be too much the diplomat and not enough the moral leader when it came to dealing with the Holocaust. The Second World War was followed by the Cold War, when the pope sought to protect the Church and the faithful from the threat of Communism in the world. In the age of totalitarianism, one response to dealing with ideological secular powers was to tighten up the teachings and beliefs of the Church, as was done by Pius xii with his new emphasis on the role and importance of Mary as the Mother of God when he enunciated the doctrine of the Assumption of Mary into Heaven in 1950 and introduced the first Marian Year in 1954.

John Pollard draws on his extensive background in papal studies to provide this depiction and delineation of an important period in papal history. As the biographer of Benedict xv, Pollard is thoroughly familiar with the sources for this papacy. He has also written extensively on the papacy of Pius xi and now demonstrates that he has examined the documents on the reign of Pius xi which have recently been opened in the Archivio Segreto Vaticano. His discussion of the papacy of Pius xi is the most valuable part of this book, as it brings together the most recent research in evaluating the significance of this papacy.

Unfortunately, because of the reluctance of the Vatican to open the documents which it holds for the reign of Pius xii, the section on Pius xii is the weakest part of this study, since Pollard has been limited to the documentation which is in the public domain, much of which has already been used in other secondary studies of Pius xii.

This book is a valuable overview of developments in the papacy in the first half of the twentieth century.