What was J.R.R. Tolkien's academic subject at the University of Leeds?

J.R.R. Tolkien taught English language at the University of Leeds.

Tolkien joined the University of Leeds in 1920 as a reader in English language. He became a professor there in 1924 and worked with E. V. Gordon on influential scholarship about the Middle English poem Sir Gawain and the Green Knight. Their edition appeared in 1925 and remains important in the study of the poem.

His Leeds period also included teaching Old English and Middle English, subjects closely related to Tolkien’s later academic career and literary interests. In 1925 he left Leeds to become Rawlinson and Bosworth Professor of Anglo-Saxon at the University of Oxford.

The answer is sometimes confused with “English literature,” a broader field Tolkien also taught and studied. His Leeds appointment was specifically connected with English language, while his Oxford posts included Anglo-Saxon and later the English language and literature of the Middle and Later periods.