The reorganization of occupied dioceses during World War II was an issue faced by Pope Pius XII of whether to extend the apostolic authority of Catholic bishops from Nazi Germany and Fascist Italy to German-occupied Europe during World War II.

Although such reorganization was often refused, the decision of Pius XII to appoint German apostolic administrators to occupied Poland was "one of his most controversial decisions". These actions were the primary justification given by the Soviet-backed Polish Provisional Government (which replaced the pro-Catholic Polish government-in-exile), for declaring the Concordat of 1925 null and void in 1945, an act that had tremendous consequences for post-war Polish-Holy See relations. There was no Apostolic Nuncio to Poland between 1947 and 1989.

History A note from Reich Ambassador to the Holy See Diego von Bergen, dated 29 August 1941, demanded that "all ecclesiastical appointments to important posts in annexed or occupied regions be first communicated to Berlin". The note was meant to apply to all "residential bishops, coadjutors with the right of succession, prelati nullius, apostolic administrators, capitular vicars, and all having equivalent functions in the government of a diocese". Explicitly included in the demand were Alsace, Lorraine, Luxembourg, Lower Styria, Carinthia, and Carniole, as Germany viewed the right of consultation on appointments granted by the Reichskonkordat as extending to occupied territory.

The Holy See explicitly refused the demand on 18 January.Blet, 1999, p. 74. Tardini wrote in August 1940: The present historical moment is very serious from this point of view: Hitler, the persecutor of the Church and the master of much of Europe, wishes in one way or another to impose the appointment of German bishops within non-German territories, and he wants to exercise and influence on the appointments, more so than previously agreed to.... What can the Holy See do? It can do what it has always done: reaffirm and defend its liberty, firmly maintain its rights against government coercion when such pressure is detrimental to the good of souls. The people will joyfully greet such apostolic firmness on the part of the Holy See and will stand close around it as the sole herald of divine truth and the sole protector of human dignity.

Albania Italy invaded Albania on Good Friday 1939.Chadwick, 1988, p. 59. By the end of the war, most of the surviving Catholic priests in Albania were of Italian origin an had been used by the fascist regime for the expansion of Italian culture and influence.Kent, 2002, p. 46. Following the Italian invasion, "the Catholic Church enjoyed a position of favour and influence throughout the Second World War". Anton Harapi, a Catholic priest, was made regent, and Maliq Bushati, a Catholic, was made prime minister. According to Kent, "in Albania, more than in any other country, the Catholic Church had been an antinational force in the service of the national enemy".

Belgium The deaneries of Eupen, Malmedy, and Moresnet, all Diocese of Liège but annexed to Nazi Germany, were subordinated to an Apostolic Administrator, first (1941–1943) Hermann Joseph Sträter, diocesan administrator of Aachen, and then (1943–1945) Johannes Joseph van der Velden, Bishop of Aachen.Akten der Partei-Kanzlei der NSDAP: Rekonstruktion eines verlorengegangenen Bestandes; Sammlung der in anderen Provenienzen überlieferten Korrespondenzen, Niederschriften von Besprechungen usw. mit dem Stellvertreter des Führers und seinem Stab bzw. der Partei-Kanzlei, ihren Ämtern, Referaten und Unterabteilungen sowie mit Heß und Bormann persönlich, Helmut Heiber (comp.) on behalf of the Institut für Zeitgeschichte (ed.), Munich et al.: Oldenbourg et al., 1983, vol. 1, part 1, p. 561. .

Czechoslovakia (western part) The heartland of Western Czechoslovakia became the Protectorate of Bohemia and Moravia of the Reich in 1939. In October 1938, the western border regions of Czechoslovakia had been dissected and annexed mostly by Nazi Germany (Sudetenland) and, to a small extent, by the Second Polish Republic (Trans-Olza, an area of Czechoslovak Silesia). These annexations had only partially been internationally recognised at the time and were reversed after World War II. Most of the people in the Budejovice diocese were of Czech ethnicity (with a small German minority).Blet, 1999, p. 95. A. Eltschkner was appointed bishop and the German government was notified even before an announcement appeared in L'Osservatore Romano.Blet, 1999, p. 96. On 24 July von Bergen demanded a bishop of German ethnicity or nationality for Budejovice (hinting his favor for J. Remiger), referencing the appointment of French bishops to Metz and Strasbourg in 1919. An investigation was conducted by the Congregation for Extraordinary Ecclesiastical Affairs, which concluded that the original appointment should be followed through.Blet, 1999, p. 97.

After the Polish takeover of Trans-Olza, never internationally recognised, the Polish government had requested the Holy See to disentangle the parishes there from either the Archdiocese of Breslau (northerly Trans-Olza) or the Archdiocese of Olomouc (southerly Trans-Olza), respectively, both traditionally comprising cross-border diocesan territories in Czechoslovakia and Germany. The Holy See complied and Pope Pius XI then subjected the Catholic parishes in Trans-Olza to an apostolic administration under Stanisław Adamski, Bishop of Katowice, who held that position until 31 December 1939.Jerzy Pietrzak, "Die politischen und kirchenrechtlichen Grundlagen der Einsetzung Apostolischer Administratoren in den Jahren 1939–1942 und 1945 im Vergleich", in: Katholische Kirche unter nationalsozialistischer und kommunistischer Diktatur: Deutschland und Polen 1939–1989, Hans-Jürgen Karp and Joachim Köhler (eds.), (=Forschungen und Quellen zur Kirchen- und Kulturgeschichte Ostdeutschlands; vol. 32), Cologne: Böhlau, 2001, pp. 157–174, here p. 160. . On 23 December 1939 Orsenigo appointed – with effect of 1 January 1940 – Breslau's Archbishop Adolf Bertram and Olomouc' Archbishop Leopold Prečan as apostolic administrators for exactly those Catholic parishes of Trans-Olza, where Pius XI had deposed them in 1938.Jerzy Pietrzak, "Die politischen und kirchenrechtlichen Grundlagen der Einsetzung Apostolischer Administratoren in den Jahren 1939–1942 und 1945 im Vergleich", in: Katholische Kirche unter nationalsozialistischer und kommunistischer Diktatur: Deutschland und Polen 1939–1989, Hans-Jürgen Karp and Joachim Köhler (eds.), (=Forschungen und Quellen zur Kirchen- und Kulturgeschichte Ostdeutschlands; vol. 32), Cologne: Böhlau, 2001, pp. 157–174, here p. 162. .

Estonia Eduard Profittlich, S.J., the apostolic administrator of Estonia, was one of many Catholic clergy victims of the Soviet deportations from Estonia in 1941. The Occupation of Estonia by Nazi Germany prevented the Catholic hierarchy from reconstituting itself although Jesuit Henri Werling was permitted to assume Profittlich's duties.

France Charles Ruch, Bishop of Strasbourg was expelled after the German annexation and could return only in 1945.

After a francophile manifestation on the occasion of the feast of the Assumption of Mary (15 August) in 1940, the Nazi occupants expelled Joseph-Jean Heintz, Bishop of Metz and he could return only in the autumn of 1944.

Hungary Hungary obtained some territory of former Romania on 29 August 1940, and in turn, it demanded ecclesiastical reorganisation. That was denied by the Holy See.

Lithuania A treaty between Lithuania and the Soviet Union brought the city of Wilno and the Wilno Region under the jurisdiction of still-independent Lithuania on 10 October 1939. The Lithuanian government requested to have Archbishop Romuald Jałbrzykowski removed from the see. The reply of Cardinal Secretary of State Luigi Maglione was that "the government of Kaunas should appreciate that the Holy See cannot run behind armies and change bishops as combat troops occupy new territory belonging to countries other than their own". Jałbrzykowski was expelled by the Germans in 1942. When auxiliary bishop Mečislovas Reinys took over Jałbrzykowski, further tension was sparked between the Poles and Lithuanians.Dunn, 2004, p. 107.

Poland

Following the occupation of Poland (1939–1945), the government of dioceses was "one of the first questions the Holy See had to face".Blet, 1999, p. 71. Many of the main sees were vacant prior to the war, including Warsaw, where Cardinal Aleksander Kakowski had died in December 1938. In Krakow, elderly Archbishop Adam Stefan Sapieha had sent his letter of resignation to the pope.

Cardinal August Hlond, the primate of Poland, was unable to return to his Archdioceses of Poznań-Gniezno and had accompanied the Polish government-in-exile to Romania and then continued to Rome. However, he had appointed vicars general to represent him, Cathedral Capitular Eduard van Blericq for Gniezno and Auxiliary Bishop Walenty Dymek for Poznań.Jerzy Pietrzak, "Die politischen und kirchenrechtlichen Grundlagen der Einsetzung Apostolischer Administratoren in den Jahren 1939–1942 und 1945 im Vergleich", in: Katholische Kirche unter nationalsozialistischer und kommunistischer Diktatur: Deutschland und Polen 1939–1989, Hans-Jürgen Karp and Joachim Köhler (eds.), (=Forschungen und Quellen zur Kirchen- und Kulturgeschichte Ostdeutschlands; vol. 32), Cologne: Böhlau, 2001, pp. 157–174, here p. 158. .

Other bishops had been forced out of their dioceses in the first days of the war such as Stanisław Okoniewski, the bishop of Chełmno-Pelplin, and Karol Mieczysław Radoński, the bishop of Włocławek. Archbishop Antoni Julian Nowowiejski of Płock diocese was killed at Soldau Concentration Kamp i Działdów. Okoniewski's auxiliary bishop Konstantyn Dominik was interned by the end of 1939. Furthermore, Radoński's auxiliary bishop Michał Kozal was arrested by the end of 1939 and eventually died in Dachau concentration camp; the auxiliary of Lublin, Bishop Władysław Goral was similarly arrested and killed in Oranienburg-Sachsenhausen as was Bishop Leon Wetmanski, the auxiliary of Płock, at Auschwitz. Indeed, the German occupants undertook a systematic policy of forcing bishops from their dioceses, interning and arresting them.

Approximately 2,600, or 20%, Polish clergy members were killed by the Nazis, including five of the six bishops of the Reichsgau Wartheland; priests were targeted for their resistance activities and cultural importance.Phayer, 2000, p. 22.Phayer, 2008, pp. 22-23. Along the Nazi-Soviet demarcation line, established by the Molotov–Ribbentrop Pact, rather than appointing new bishops in the newly dissected dioceses, the bishops of neighboring diocese were made to serve as apostolic administrators. The apostolic administrators, in turn, were to designate two priests who could replace them in the event of their death or arrest.Blet, 1999, p. 72.

Almost immediately, the Reich's ambassador to the Holy See, Diego von Bergen, made it clear that Nazi Germany would like to see German prelates made temporary administrators of the sees whose bishops had been deposed. Prelate Franz Hartz, German Territorial Prelature of Schneidemühl, was suggested by the ambassador as administrator for Gniezno-Poznań, Danzig's Bishop Carl Maria Splett for Chełmno-Pelplin, and Breslau's Archbishop Adolf Bertram for Katowice, which had been disentangled from his see in 1922. According to Monsignore Domenico Tardini, Pius XII "acknowledging the soundness of this proposal, has decided to postpone it". Except for Splett, the Holy See did not take up any of the proposals.