J. R. R. Tolkien made use of pseudotranslation in The Lord of the Rings for two reasons: to help resolve the linguistic puzzle he had accidentally created by using real-world languages within his legendarium, and to lend realism by supporting a found manuscript conceit to frame his story.
Thomas Honegger gives possible solutions that begin to handle this in French and German, but suggests that the small amount of Old English is probably best left untranslated.
From his schooldays, J. R. R. Tolkien was, in the words of his biographer John Garth, "effusive about philology"; his schoolfriend Rob Gilson called him "quite a great authority on etymology".
The practice began in medieval chivalric romance, and was common in 16th-century Spain, in works like the c. 1508 Amadís de Gaula; it was mocked by Cervantes in his 1605 Don Quixote.
"Veggr ok Gandalfr, Vindalfr, Þorinn, Þrár ok Þráinn, Þekkr, Litr ok Vitr, 11.... Nar and Nain, | Niping, Dain, Bifur, Bofur, | Bombur, Nori, ... 12.
Tolkien needed to find a solution that would make names in Norse and Khuzdul – one real language, one invented – coexist.
[T 3] He went on to explain why he had done this:[T 3] [I wished to preserve] the contrast between a wide-spread language... and the living remains of far older and more reverend tongues.
[T 3]Tolkien gave as a picture of the reason for this approach a sentence mapping Middle-earth to the real world, though with the inclusion of the semi-mythical figure of King Arthur:[T 3] But to refer to Rivendell as Imladris was as if one now was to speak of Winchester as Camelot, except that the identity was certain, while in Rivendell there still dwelt a lord of renown far older than Arthur would be, were he still king at Winchester today.
Since the Rohirrim are represented as recent comers out of the North, and users of an archaic Mannish language relatively untouched by the influence of Eldarin, I have turned their names into forms like ... Old English.
[T 3] The device of linguistic mapping allowed Tolkien to avoid having to invent new names in Khuzdul for all his Dwarves, while simultaneously explaining the book's use of Modern English for Westron.
At times some Rider would lift up his clear voice in stirring song, and Merry felt his heart leap, though he did not know what it was about.
The people of Rohan, the Rohirrim, speak a Mercian dialect of Old English, and their culture is Anglo-Saxon, despite Tolkien's denial of this in "On Translation".
[T 2] In the related case of the Book of Mazarbul, which was found lying on Balin's tomb,[T 9] Tolkien admitted that he had made a mistake using English in his facsimile document, "an erroneous extension of the general literary treatment",[T 10] since the writing was "supposed to be of the date of the events in the narrative".
He described in detail how Bilbo and Frodo Baggins wrote their memoirs, transmitted them to others as the Red Book of Westmarch, and showed how later in-universe editors annotated the material.
[19] Tolkien then appears not as the book's author but as editor and translator, the text as a survival through long ages, and the events depicted as historical.