J.R.R. Tolkien’s Oxford academic field before his professorship in English was Anglo-Saxon, also called Old English.
In 1925, Tolkien became Rawlinson and Bosworth Professor of Anglo-Saxon at the University of Oxford. The position reflected his expertise in early Germanic languages and literature, including Old English texts such as Beowulf. He later became Merton Professor of English Language and Literature in 1945.
Tolkien’s scholarly work was not separate from his creative writing. His study of historical languages, sound changes, word origins, and medieval stories helped him construct believable languages and cultures for Middle-earth. Old English also influenced names and terms associated with the Rohirrim, whose language and culture draw heavily on Anglo-Saxon models.
“Anglo-Saxon” in this context means the language and literature of early medieval England, not a modern literary genre. Tolkien was a philologist: a scholar concerned with language in its historical and cultural setting.