Vatican / Papa Pius XII (Pope Pius XII)

Pope Pius XII (Italian: Pio XII), born Eugenio Maria Giuseppe Giovanni Pacelli, was head of the Catholic Church from 2 March 1939 to his death in 1958. Before his election to the papacy, Pacelli served as secretary of the Department of Extraordinary Ecclesiastical Affairs, papal nuncio to Germany (1917–1929), and Cardinal Secretary of State, in which capacity he worked to conclude treaties with European and Latin American nations, most notably the Reichskonkordat with Nazi Germany, with which most historians believe the Vatican sought to protect the Church in Germany while Adolf Hitler sought the destruction of "political Catholicism". A pre-war critic of Nazism, Pius XII lobbied world leaders to avoid war and, as Pope at the outbreak of war, issued Summi Pontificatus, expressing dismay at the invasion of Poland, reiterating Church teaching against racial persecution and calling for love, compassion and charity to prevail over war.

While the Vatican was officially neutral during the war, Pius XII maintained links to the German Resistance, used diplomacy to aid the victims of the war and lobby for peace, and spoke out against race-based murders and other atrocities. The Reichskonkordat of 1933 and Pius's leadership of the Catholic Church during World War II remain the subject of controversy - including allegations of public silence and inaction about the fate of the Jews. After the war, Pius XII advocated peace and reconciliation, including lenient policies towards Axis and Axis-satellite nations. Pius XII was also a staunch opponent of Communism and of the Italian Communist Party. During his papacy, the Decree against Communism was issued by the church; the decree declared that Catholics who profess Communist doctrine are to be excommunicated as apostates from the Christian faith. In turn, the Church experienced severe persecution and mass deportations of Catholic clergy in the Eastern Bloc. He explicitly invoked ex cathedra papal infallibility with the dogma of the Assumption of Mary in his 1950 Apostolic constitution Munificentissimus Deus.

In 1954, Pius XII began to suffer from ill health, which would continue until his death in 1958. He was buried in the Vatican grottos and was succeeded by Pope John XXIII.