In Welsh legend, corgis were once the steeds of the fairy folk. ​You can still see the faint markings of the fairy saddles across the Pembroke Welsh Corgi's shoulders and back... or so I've heard. I found many books and websites which mentioned the "ancient legend," but none provided a source. Conversely, I could not find any books of Welsh legend that mentioned the corgi's enchanted origins. It's an orphaned fun fact. 
 
Welsh Corgis have been around for a long time. They were bred as cattle dogs, whose small stature helped them avoid the cows' kicking hooves, but they worked with all sorts of livestock. In the 1920s, their name came into more widespread use and they were officially acknowledged as a breed. The English Kennel Club formally recognized the two Corgi breeds, Pembroke and Cardigan, as separate in 1934.

There are many theories on where their name came from. One is that it is a compound meaning ​"dwarf dog": cor (dwarf) + ci (dog). Some modern sources connect this to the Little Folk.
This debate is not new. The Dictionary of the Welsh Language by William Spurrell (1853) defined corgi as a "cur dog." The "cur dog" definition might have more historical support, going back as far as 1574 in William Salesbury’s Dictionary in Englyshe and Welshe. Here, cur would just be used in the sense of a dog of low breeding: a working dog as opposed to a lapdog.  In A Dictionary of the Welsh Language (1893), Daniel Silvan Evans defended the "dwarf dog" definition, which is more widespread today. However, he was not using "dwarf" in the sense of fairy. He just meant it was a small dog.

So when did the fairy saddle legend originate?

The earliest source I can find is the poem "Corgi Fantasy" by Anne G. Biddlecombe of Dorset, England. She was one of the top Pembroke breeders  of the 1940s and 1950s, and a founding member of the Welsh Corgi League in London, serving as their secretary for some time.​ She used the pedigree prefix Teekay, under which many of her dogs became show champions.

The poem was first published in 1946 (in the first edition of the Welsh Corgi League Handbook?). Two children find some foxlike puppies out in the woods and take them home. Their father tells them that the dogs are a gift from the fairies, who ride them or use them to pull coaches and herd cows. He points out the image of the fairy saddles on the dogs' coats.

This poem soon became popular and was reprinted in numerous magazines and books, crossing over from England to America. It featured at least twice in the American Kennel Gazette, in 1950 and 1956. The artist Tasha Tudor drew illustrations when it appeared in the Illustrated Study of the Pembroke Welsh Corgi Standard (1975).
(Tudor was a well-known fan of Corgis. In the introduction to her 1971 picture book Corgiville Fair, she said, "They are enchanted. You need only to see them by moonlight to realize this.")

Other modern corgi enthusiasts added their own twists with books, poems and stories like "The Fairy Saddle Legend" and "How the Corgi Lost his Tail​." Many artists have turned their talents to drawing corgis with fairies. The stories mention the corgis serving as the fairies' battle steeds - a fantastic mental image.
As an interesting sidenote, the Pembroke Welsh Corgi Club of America uses the acronym PWCCA. The pwca or pooka is a mischievous spirit in Welsh folklore.

Pembrokes weren't the only ones with otherworldly connections. "Rhodd Glas: The Blue Gift," by Pam Brand, appeared in the 1996 handbook of the Cardigan Welsh Corgi Club of America. Brand described how the fairies created the first blue merle Cardigan corgi from a wildflower. 

Some even say that corgis were used in a war between the Tylwyth Teg and the Gwyllion, but this is hard to verify. In fact, these two fairy types may be the same thing, not separate tribes at all. The farthest I could trace that particular variation was the book Gods, ghosts and black dogs: The fascinating folklore and mythology of dogs,​ published in 2016. Later that same year, a Mental Floss article "The Ancient Connection Between Corgis and Fairies" used the story.

You may notice that none of these sources are from fairytales or folklore collections. Instead, they're from articles on dog breeds. At this point, I have found no ancient tales of fairies riding any kind of dog. However, I have found a few Welsh legends of fairy steeds.
​In "The Tale of Elidorus," from Giraldus Cambrensis' account in 1191, the little people rode miniature horses perfectly adapted to their size. They had similarly tiny greyhounds. 
In Thomas Crofton Croker's Fairy Legends (1828), a woman from the Vale of Neath saw an army of fairies "mounted upon little white horses, not bigger than dogs." That's at least a small step closer to the corgi legend.

Based on all this, I would guess that the legend of the corgi's fairy origins is new, not ancient. It's a modern folktale which grew naturally out of the subculture of corgi breeders and fans. The idea of the "saddle marks" took shape around the time the dog's characteristics were being formally defined. The "Corgi Fantasy" poem was published twelve years after the Pembroke breed was recognized. Other people came up with their own spins on the story, and it developed from there.

I'm currently working on a timeline of the corgi legend's evolution. Many of these poems and stories were first printed in dog magazines and handbooks, which makes them difficult to track down. If you have any clues, please send them in!
 
​Sources

• "Corgi Fantasy," by Anne G. Biddlecombe. 1946.
• Giraldus Cambrensis, The Itinerary of Archbishop Baldwin Through Wales, 1191. Trans. David Price, 1912. pg. 69.
• Croker, Thomas Crofton. Fairy legends and traditions of the South of Ireland vol III. 1828. pg. 205. [This seems to be one of the stories that he received via Thomas Keightley.]
• Coren, Stanley. Gods, ghosts and black dogs: The fascinating folklore and mythology of dogs. 2016. "The war steeds of the fairies," pp. 73-77.
• Gray, Thelma. The Welsh Corgi League, Founded 1938. 
• Corgi Tracks 2015-2016. Brief information about Anne G. Biddlecombe a few pages in.

Widespread through English folklore are black dogs and hellhounds: ghostly presences which terrify people and are portents of death. You have your Grims, your Padfoots, your Black Shucks, and your Freybugs, along with many others.

The Freybug, the black dog of Norfolk, has featured in the video game Final Fantasy and in the Dracopedia series. But there are some concerns.

As pointed out by the blog A Book of Creatures (which I stumbled across while researching other monsters), the freybug first appeared in the work of Carol Rose, specifically her books Spirits, Fairies, Gnomes and Goblins ​(1996) and Giants, Monsters, and Dragons (2000). According to ​Spirits, Fairies, Gnomes and Goblins, ​the Freybug is "a demon of the roads in English folk beliefs of the Middle Ages. It was described as a Black Dog fiend and referred to in an English document of 1555."

Rose cites no sources. What document of 1555? Where did she get this? ​There are no other sources for the Freybug, and she actually cited herself ​when she included it in her later book. That is a bad sign.

However, the root words are familiar. "Fray" means fear or panic. ​"Bug" is a hobgoblin. As a result, Freybug sounds very . . . Denham Tracts-y. 
The Denham Tracts were a series of pamphlets by Michael Aislabie Denham from the 1840s and 1850s. They include a walloping list of monsters including, but not limited to: bogies, boggles, boggleboes, boggy-boes, boggarts, barguests, bygorns, bugbears, black-bugs, scar-bugs, ​bugaboos, ​and bugs.

​A while after I learned about the Freybug, I was looking at my Denham Tracts list again, and one jumped out at me: the Flay-Boggart. This was a word for a scarecrow, but could also apply to a generic frightening monster. It appeared at least as early as 1535, in the Coverdale Bible's Epistle of Jeremiah: "For like as a frayboggarde in a garden off Cucumbers kepeth nothinge, even so are their goddes of wod, of syluer & golde." 

​Rose's books are the only sources for the Freybug. ​But what about Fraybug?

It turns out that English martyr Laurence Saunders twice mentioned "fray-bugs" in his letters.

The word was defined by The Church Historians of England: Reformation Period (1859) as an "imaginary monster" and by Letters of the martyrs of the English Church (1884) as a "spectre." 

Saunders' letters were written in 1555 - the year so mysteriously cited by Rose.

Under the spellings fray-bug, frai-bugge, and fray-buggard, the word occurs in multiple works from the 16th and 17th centuries - it's in the Oxford English Dictionary and everything. It was also used as a verb, as in "to frighten someone." In the conclusion to book 2 of John Bale's  The actes of Englysh votaryes (1551): "They fraybugged the' with the thundreboltes of theyr excommunycacyons and interdiccyons."

Based on these books, and the date of Saunders' letters, things were looking much better for the Freybug - although there was still no tie to black dogs. 

​And then I found John Brand's Popular Antiquities of Great Britain vol. 1 (1905). This book describes black dogs such as the Barguest or the boggart of Lancashire, and then suggests (bewilderingly), "This dog-spirit may be the malignant influence referred to under the name of Fray-bug, in a curious extract from a letter of Master Saunders to his wife, 1555."

There ​it is. I suspect that Carol Rose read ​Popular Antiquities, didn't know who Saunders was, but decided to use the creature in her book anyway. She misspelled the name and fudged the citation (it's not like Brand cited things clearly to begin with). When she returned to the subject in her later book, she rephrased it as "an English manuscript of 1555," something rather different from a letter, which would be even more confusing to anyone who later tried to fact-check it.

I can't say whether the fray-bug was in fact supposed to be a black dog. I would tend to think it's a generic boogeyman, perhaps resembling a scarecrow, although there can be overlaps between black dogs and other apparitions. The black dog called freybug is a new creation, but the fray-bug has been around for hundreds of years.