In the run-up to the Second World War, Tolkien was earmarked as a codebreaker.
In January 1939, he was asked whether he would be prepared to serve in the cryptographic department of the Foreign Office in the event of national emergency.
He replied in the affirmative and, beginning on 27 March, took an instructional course at the London HQ of the Government Code and Cypher School.
A record of his training was found which included the notation "keen" next to his name, although Tolkien scholar Anders Stenström suggested that "In all likelihood, that is not a record of Tolkien's interest, but a note about how to pronounce the name."
He was informed in October that his services would not be required.

In 1945, Tolkien moved to Merton College, Oxford, becoming the Merton Professor of English Language and Literature, in which post he remained until his retirement in 1959.
He served as an external examiner for University College, Dublin, for many years.
In 1954 Tolkien received an honorary degree from the National University of Ireland (of which U.C.D. was a constituent college).
Tolkien completed The Lord of the Rings in 1948, close to a decade after the first sketches.
In the run-up to the Second World War, Tolkien was earmarked as a codebreaker. In January 1939, he was asked whether he would be prepared to serve in the cryptographic department of the Foreign Office in the event of national emergency. He replied in the affirmative and, beginning on 27 March, took an instructional course at the London HQ of the Government Code and Cypher School. A record of his training was found which included the notation "keen" next to his name, although Tolkien scholar Anders Stenström suggested that "In all likelihood, that is not a record of Tolkien's interest, but a note about how to pronounce the name." He was informed in October that his services would not be required.
In 1945, Tolkien moved to Merton College, Oxford, becoming the Merton Professor of English Language and Literature, in which post he remained until his retirement in 1959. He served as an external examiner for University College, Dublin, for many years. In 1954 Tolkien received an honorary degree from the National University of Ireland (of which U.C.D. was a constituent college). Tolkien completed The Lord of the Rings in 1948, close to a decade after the first sketches.
J. R. R. Tolkien