Which medieval poem did J.R.R. Tolkien translate and lecture about at Oxford?

J.R.R. Tolkien translated and lectured about the medieval poem Sir Gawain and the Green Knight at Oxford.

The poem survives in a single late-fourteenth-century manuscript and tells of Sir Gawain, a knight of King Arthur’s court, who accepts the Green Knight’s beheading challenge. Tolkien worked on the poem with E.V. Gordon, and their scholarly edition was published in 1925. Tolkien’s translation was published posthumously in 1975.

The work mattered to Tolkien both as a scholar and as a writer. Its alliterative verse, moral testing, supernatural imagery, and detailed medieval setting show the kinds of traditions he studied closely. Tolkien also delivered a well-known lecture on the poem, emphasizing its unity and artistic design rather than treating it as a disconnected collection of episodes.