German historian, archivist and librarian, who published numerous books.
The son of a merchant banker and brother of the writer Franz Hessel he studied history, philosophy and economics from 1895 in Heidelberg, Munich and Berlin, where he received his doctorate in 1899. In the following years Hessel was a freelancer with Paul Fridolin Kehrs in the study of medieval papal documents. From 1901 to 1908 he worked in Strasbourg as a colleague of Harry Bresslaus on the publication of the documents of Conrad II for the Monumenta Germaniae Historica. As a further result of his research in Italian libraries and archives, he published in 1910 a history of Bologna in the 12th and 13th centuries, with his habilitation in 1914 at the University of Strasbourg for Middle and Modern History. From 1909 until the beginning of the First World War Hessel worked on behalf of the Historical Commission of Alsace.
From 1914 to 1918 Hessel was a soldier, first as a voluntary nurse, then in art protection in occupied northern Italy. Since he could not return to Strasbourg in occupied France, he habilitated at the University of Göttingen, where he taught from 1919 as a private lecturer, and from 1922 with the title “Extraordinary Professor”. While Hessel had been economically independent before the war because of his paternal inheritance, he was now dependent on a regular income. Because a salaried professorship at the university was not available, he received, at the suggestion of Karl Brandis, a position from 1922 as a librarian in the manuscript department of the University Library Göttingen. Hessel was at the same time since 1924 co-director of the diplomatic apparatus, a palaeographical teaching collection, and arranged the archives of the Göttingen Academy of Sciences and the University Library. In 1926 he was also honorary professor at the Faculty of Arts, 1928 co-editor of the archive for document research founded by Karl Brandi. He worked in the fields of paleography, medieval history and library history.
Because of his Jewish descent, Hessel was fired from his teaching duties in 1935 and forcibly retired as a librarian. He also had to give up the editorship of the archive for document research and was not allowed to use any libraries from 1938. The history of the Göttingen University Library, which was published for the 200th anniversary in 1937, with text he had written in large part, did not appear under his name. At the end of 1938, Hessel seems to have made the decision to emigrate from Germany and made contacts in Great Britain, but until his death on 18 May 1939, these failed to achieve any result. Although Protestant since 1895, Hessel was buried in the Jewish cemetery in Göttingen. His scientific estate, which he willed to his housekeeper, was lost.
Link to Wikipedia biography (German)