Which university employed C. S. Lewis before his Cambridge appointment?

Oxford University employed C. S. Lewis before his Cambridge appointment.

Lewis’s academic career was closely associated with Oxford, where he studied and later taught English literature. In 1925 he became a fellow and tutor at Magdalen College, Oxford, and remained there for nearly three decades. His Oxford years included important scholarship, fiction, apologetics, and participation in the Inklings.

In 1954 Lewis became the first holder of the newly created chair of Medieval and Renaissance English at Magdalene College, Cambridge. The move did not erase his Oxford connection: he continued to live near Oxford, at The Kilns, and traveled to Cambridge for his teaching duties.

The question asks about the university before Cambridge, so Oxford University is the specific answer. Magdalen College belongs to Oxford, while Magdalene College is the Cambridge college. Their similar names are a frequent source of confusion, especially because Lewis taught at one of each during different stages of his career.