On 3 November 1920, Tolkien was demobilized and left the army, retaining his rank of lieutenant.
His first civilian job after World War I was at the Oxford English Dictionary, where he worked mainly on the history and etymology of words of Germanic origin beginning with the letter W. In 1920, he took up a post as reader in English language at the University of Leeds, becoming the youngest professor there.
While at Leeds, he produced A Middle English Vocabulary and a definitive edition of Sir Gawain and the Green Knight with E. V. Gordon; both became academic standard works for several decades.
He translated Sir Gawain, Pearl, and Sir Orfeo.
In 1925, he returned to Oxford as Rawlinson and Bosworth Professor of Anglo-Saxon, with a fellowship at Pembroke College.

In mid-1919, he began to tutor undergraduates privately, most importantly those of Lady Margaret Hall and St Hugh's College, given that the women's colleges were in great need of good teachers in their early years, and Tolkien as a married professor (then still not common) was considered suitable, as a bachelor don would not have been.

During his time at Pembroke College Tolkien wrote The Hobbit and the first two volumes of The Lord of the Rings, while living at 20 Northmoor Road in North Oxford (where a blue plaque was placed in 2002).
He also published a philological essay in 1932 on the name "Nodens", following Sir Mortimer Wheeler's unearthing of a Roman Asclepeion at Lydney Park, Gloucestershire, in 1928.
On 3 November 1920, Tolkien was demobilized and left the army, retaining his rank of lieutenant. His first civilian job after World War I was at the Oxford English Dictionary, where he worked mainly on the history and etymology of words of Germanic origin beginning with the letter W. In 1920, he took up a post as reader in English language at the University of Leeds, becoming the youngest professor there. While at Leeds, he produced A Middle English Vocabulary and a definitive edition of Sir Gawain and the Green Knight with E. V. Gordon; both became academic standard works for several decades. He translated Sir Gawain, Pearl, and Sir Orfeo. In 1925, he returned to Oxford as Rawlinson and Bosworth Professor of Anglo-Saxon, with a fellowship at Pembroke College.
In mid-1919, he began to tutor undergraduates privately, most importantly those of Lady Margaret Hall and St Hugh's College, given that the women's colleges were in great need of good teachers in their early years, and Tolkien as a married professor (then still not common) was considered suitable, as a bachelor don would not have been.
During his time at Pembroke College Tolkien wrote The Hobbit and the first two volumes of The Lord of the Rings, while living at 20 Northmoor Road in North Oxford (where a blue plaque was placed in 2002). He also published a philological essay in 1932 on the name "Nodens", following Sir Mortimer Wheeler's unearthing of a Roman Asclepeion at Lydney Park, Gloucestershire, in 1928.
J. R. R. Tolkien