Robert Leiber Collection

Robert Leiber S.J. (1887–1967): A Biographical Note

Robert Leiber was born on 10 April 1887 in Oberhomberg, near Überlingen, the fifth child of the local elementary school teacher Wendelin Leiber and his wife Katharina, née Locher.

In 1905–06 he studied theology for two semesters as a resident student (Konviktor) in Freiburg, Burgstraße 1. He entered the Jesuit novitiate in Mainz in 1906, and from 1908 to 1911 studied philosophy in Valkenburg. He then spent several years in Copenhagen, where he had the opportunity to attend the lectures of Kristian Erslev (1852–1930), professor of history at the University of Copenhagen and the founding figure of Scandinavian source criticism (kildekritik), author of the foundational manual Historisk Teknik. Den historiske undersøgelse fremstillet i sine grundlinier (1911). This early exposure to Erslev's source-critical method offers a direct explanation for an otherwise curious biographical detail: why, after the war, Leiber would go on to teach courses in historical methodology (Geschichtliche Methodenlehre), first at Valkenburg and later at the Gregoriana. He was meant to obtain academic degrees for the Danish school where he taught, but this was prevented by the outbreak of the First World War.

In 1914–15, he studied theology for one year in Valkenburg before being assigned to Field Hospital 51 (Kriegslazarett 51), a mobile German military hospital that followed the front. Until October 1916, he served in Jarosław (Galicia), Wołkowysk and Novogrudok in northern Poland, Kevevára in southern Hungary, Kumanovo in Serbia, and finally Piennes, France, behind Fort Vaux at Verdun. A record preserved in the Worms City Archives confirms that the unit was stationed there in late 1916. In October 1916, he was discharged and returned to Valkenburg because of illness. There, on 12 August 1917, he was ordained a priest.

He subsequently pursued private study in Valkenburg and study at the University of Berlin under three of the leading German historians of the period: Michael Tangl (1861–1922), a medievalist and diplomatist; Dietrich Schäfer (1845–1929), a specialist in medieval German and Scandinavian history; and Friedrich Meinecke (1862–1954), arguably the most important German historian of political and historical thought of the early twentieth century. Together with his earlier training under Erslev in Copenhagen, this Berlin formation in diplomatics, source criticism, and the history of ideas gave Leiber an unusually rigorous methodological grounding for the archival work that would define much of his later career.

From 1930 to 1939 he taught in the Faculty of Theology and took in the newly founded Faculty of Church History of the Pontifical Gregorian University. Only when Cardinal Pacelli was elected pope in 1939 did he demand that Fr. Leiber be entirely at his disposal; from then on Leiber kept up at the Gregoriana only the lecture course and seminar on historical methodology. Throughout the whole period from January 1930 until summer 1959 he lived at the Gregoriana and drove to the Vatican every day. His name never appears in the Pontifical Yearbook, which otherwise records Vatican personnel down to the lowest ranks, and he never held any formal Vatican office.

The relationship with Eugenio Pacelli began in 1924, when Leiber, then employed by Ludwig von Pastor on his history of the popes, was asked by Pacelli — at the time nuncio in Munich — to locate archival documents needed for concordat negotiations. From early 1925 he worked consistently for the nuncio without any formal appointment, following him to Berlin and then back to Rome when Pacelli was named Secretary of State in 1930. After Pastor's death in 1928, the publisher Herder announced in 1933 that Leiber would write an independent continuation of Pastor's history of the popes covering the nineteenth century; the work was never published. With Pacelli's election as pope in 1939, Leiber's teaching at the Gregoriana was reduced to two mornings per semester, while he devoted himself almost entirely to service at the Vatican, including at Castel Gandolfo.

Throughout the period from 1939 to 1958, Leiber appears to have played a significant though largely undocumented role. Vatican wartime documents published in 1966 show that the drafts of Pius XII's German-language letters to German bishops were prepared by Msgr. Ludwig Kaas (1881–1952) and Leiber, and that the two 1939 meetings between the pope and the four German cardinals were recorded by the "private secretariat of Pius XII" — identified as Leiber alone. During the war, he is documented as having served as the liaison between the German resistance and the pope, a channel that allowed Belgium, Holland, and Luxembourg to be warned of the date of the German invasion one week in advance.

Leiber is also linked to the commemorative address for the 200th anniversary of the death of Benedict XIV, prepared for delivery in 1958 but never given due to the pope's death, and later published in the Osservatore Romano in April 1959. Following Pius XII's death, Leiber withdrew to the Pontifical Germanic-Hungarian College in Rome. He had earlier published an obituary essay on Pius XII in Stimmen der Zeit (vol. 119, 1958), and is recorded as having opposed the cause for Pius XII's canonization.

Leiber died on 18 February 1967 following surgery for a throat tumor, and was buried on 21 February at the Campo Verano cemetery (Rome), in the grave of the Society of Jesus.

The Collection

Following a preliminary inventory, it has been possible to reconstruct the arrangement of the material. A thorough investigation will be required to reconstruct the history and formation of the fonds, establishing when and by whom it was organized into the form in which it survives today.
The correspondence of the Fondo Leiber is preserved mainly in 19 folders arranged alphabetically, comprising 3,000 documents. The rest of the fund — still largely unexplored, consisting of a further 10 folders — is made up of lecture notes, drafts of articles or conference papers, bibliographical annotations, newspaper clippings and journal offprints. A large proportion of these documents bear manuscript annotations added at later dates, testifying to the fact that this material functioned as a working archive subject to continuous intervention. The documents span a chronological range from the early 1920s to Leiber's death. In terms of their material form, they consist of manuscripts, typescripts (often in shorthand) and printed items. Photographs and materials in non-paper formats are extremely rare.

Nuncio Eugenio Pacelli (later Pius XII) after the conclusion of the Prussian Concordat, Berlin, 1929. Wikimedia Commons identifies the accompanying figure as Father Robert Leiber SJ; however, this attribution is uncertain: the prelatial sash worn by the second figure is incompatible with Leiber's status, as he never held any prelatial rank or title, and a facial comparison with a verified portrait of Leiber yields no conclusive resemblance. Source: Wikimedia Commons (public domain).

Research Perspectives

The Fondo Leiber lends itself to many different historiographical approaches: from the history of diplomacy to institutional history, from biographical research to the history of theology and political thought. The following note does not attempt to survey them all. It presents instead one methodological perspective among many — one concerned with the epistemological foundations of archival research as such — that this collection renders with particular acuity, using the controversy over Pius XII's public silence during the Holocaust as its most visible illustration, without being reducible to it.

The traditional assumption underlying much of the debate — that documents function as windows, however partial, onto the consciousness of those who produced them — deserves scrutiny. A document is not the trace of a thought: it is the product of a communicative operation that selects, adapts, and reshapes whatever processes may be occurring in the mind of its author according to the conventions and expectations of the context in which it circulates. The diplomatic memorandum, the private note, the academic lecture, and the broadcast script are not four ways of saying the same thing: they are four distinct objects, each shaped by the register and institutional setting in which it operates. What the historian finds in an archive is not the consciousness of a historical subject, but the traces of his or her communications — which is an importantly different thing.

This distinction has direct consequences for how the Fondo Leiber invites being read. The most substantial thematic thread running through folders 12–20 is Leiber's sustained response to the controversy provoked by Hochhuth's Der Stellvertreter (1963): drafts, lecture transcripts, and stenographic notes in which he repeatedly reworked the same set of arguments — the pope's knowledge of the Holocaust, the reasons for his public silence, the reliability of available information — adapting them to the formats and audiences of different communicative contexts. These are not progressive approximations to the truth about Pacelli's mind: they are successive constructions, each shaped by the register and expectations of the institutional setting in which it was produced.

The broader debate between accusers and defenders of Pius XII shares a common and problematic premise: that it is possible, in principle, to establish what the pope knew, intended, and chose. Accusers and defenders differ only in the conclusions they draw from this premise. The structure is in both cases identical, and identically paradoxical: every newly opened archive reignites the debate without closing it, because the debate is structured in a way that documents cannot resolve. Documents are communications, and communications do not give access to consciousness.

The historically productive question is therefore not "what did Pius XII think?" but rather: which communicative operations were selected, by whom, in which institutional setting, and with what effects? Examined from this perspective, the Fondo Leiber becomes less a repository of testimony and more a documentation of the process by which historical meaning is produced, contested, and never finally closed. Leiber's papers record a prolonged communicative construction through which an institutional memory elaborated, over decades, an inaccessible interiority — and it is precisely as such that they constitute a source of exceptional methodological interest for the historiography of the twentieth-century Church.

Digitization and metadata description

In 2025, in collaboration with the US Holocaust Memorial Museum of Washington and the Yad Vashem, The World Holocaust Remembrance Center, a project aimed at the full digitization of an initial section of the Leiber Collection was launched.

This documentation consists of correspondence, newspaper articles, reports, handwritten notes and drafts, divided into 732 alphabetically ordered folders containing 3,500 documents, for a total of nearly 12,000 pages.

Researchers could navigate the fund trough the Indexes of the Folders and Identified Names and a keywords Resarch through the search bar below:

Indexes

Folders Index

This section provides access to the digital entries of the Robert Leiber S.J. correspondence, organized by folder. Within this category, researchers can find descriptive file pages, where each entry links to a specific folder. These include, for example, correspondence folders or files dedicated to specific recipients and topics. By clicking on the individual pages collected in this category, users can view the analytical metadata of each folder. This includes information on senders and recipients, the dating and places of origin, the document types and links to the digital images of the original documents. Furthermore, through the platform's annotation system, these pages connect the folders to semantic entities (historical figures, places and key concepts mentioned within the documents).

Names Index

This section contains and organizes an alphabetical directory of digital entries, each representing a specific person mentioned in the correspondence, reports or notes of the archive. Within this category, researchers can access dedicated biographical pages for each individual. These pages act as dynamic authority records that provide essential biographical information, including dates, institutional roles a and brief contextual backgrounds. By opening the individual profile pages collected in this index, users can explore the semantic connections of each person. Most importantly, the system provides automatic backlinks showing exactly which folders, correspondence files or specific documents contain references to that person.

FORM for the creation of new folders (Restricted use)

Until the end of the project, the physical consultation of the fund is SUSPENDED. If any researcher or research institution is interested in taking part into the project, they are welcome to submit they're request by filling up the form Request.

Bibliography

Project stages

• ☑ Conditioning and Conservation [November 2025 - May 2026]
  

The 3,500 documents held in the correspondence section of the Leiber collection were restored at the in-house conservation laboratory of the Gregorian Historical Archive. The main stages of the restoration included:

• dry cleaning;
• removal of staples and clips;
• removal of adhesive tape;
• filling in of losses;
• repair of tears and cuts;
• consolidation of fragile edges;
• colour matching of the fillings;
• re-housing.

• ☑ Digitisation [April - June 2026]
  

The complete digitisation of the documents included in the Correspondence section of the Leiber's fund was carried out in the Historical Archive’s digital reproduction area; all the digitised images were saved in TIFF and PDF formats and marked with a custom watermark.

• ☐ Metadata and semantic entities [April 2026 - current]
  

The metadata tagging and semantic annotation of the digitised files is currently underway and can be viewed in the Names Index and Folders Index pages.

• ☐ Transcription and annotation
  

The final stages of the project involve the full transcription of the documents in the collection and making them accessible to researchers. The collaborative feature of the platform allows authorised researchers and scholars to add comments, annotations and links to the digitised material.

Copyrights

Unless otherwise indicated, all files and contributions (transcriptions, pages, comments) uploaded and submitted to GATE by administrators and users are considered to be released under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. All the rights on the images of the manuscripts or other documentation are property of the Historical Archives of the Pontifical Gregorian University (User:ArchivesPUG). If you need high resolution images for your publications or for other usages, please contact us using this form.

Your contributions to GATE must be original or, at most, copied from public domain or similar free sources. Remember to always cite your sources and, more important, do not submit copyrighted work without permission.

References