THE TRANSFORMATION OF UTHER PENDRAGON

In Muirchu, while it is Patrick who prays for the removal of Coroticus, it is the king's own men who work his transformation.  And what they do with the recitation of the "poem" sounds suspiciously like the casting of a druidic spell or curse.  The Latin reads:

"Non grande post ea tempus effluxerat et musi-cam artem audiuit a quodam cantare quod de solio regali transiret, omnesque karissimi eius uiri in hanc proruperunt uocem."

The word 'cantare' here implies not only a song, but also an 'incantation, charm, spell, magic song.'

According to Welsh Triad 28, Uther was a great enchanter.

TRIAD 28

Three Great Enchantments of the Island of Britain:

The Enchantment of Math son of Mathonwy (which he taught to Gwydion son of Don), and the Enchantment of Uthyr Pendragon (which he taught to Menw son of Teirgwaedd), and the Enchantment of Gwythelyn/Rudlwm the Dwarf (which he taught to Coll son of Collfrewy his nephew).

In "Math Son of Mathonwy", the title character transforms Gwydion and Gilfaethwy into deer, pigs and wolves.  Gwydion transforms the eagle Lleu back into human form.  In TRIAD 27, Coll son of Collfrewy is named as a great enchanter.  In 26, he is one of the great swineherds.  He owned a magical sow who gave birth to wheat, bees, barley, a wolf-cub, an eagle and the dreaded Palug's cat.

The Menw mentioned above tranforms himself into a bird in "Culhwch and Olwen":

"And Menw transformed into the form of a bird, and landed over his lair, and tried to snatch on of the treasures from him. And he got nothing, however, apart from one of his bristles."

Bromwich's note (b) to TRIAD 28 points out that "Menw m. Teirgwaedd is distinguished as a shapeshifter."  She makes the case for Uther's transformation being that into Gorlois, recorded in Geoffrey of Monmouth's pseudo-history.

However, given that all the transformations alluded to involve animals, we cannot help but wonder whether Uther's was of the same kind.  Did he, perhaps, turn into a fox?

We need to take another look at the relevant lines of "Marwnat Vthyr Pen", where the hero calls himself gorlassar:

It is I who commands hosts in battle:
I’d not give up between two forces without bloodshed.
It’s I who’s called the very blue [or, given the context, 'the great blaze, conflagration'; cf. Irish forlassar, from the intensive prefix plus lasar, 'fire, flame']:
my ferocity snared my enemy.
It is I who’s a leader in darkness:
Our God, Chief of the Sanctuary, transforms me.
It’s I who’s like ['eil' here means like/similar to, not 'second' - unless God is to be considered the 'first'] a candle/luminary [transf. star, sun, moon; fig. leader, hero] in the gloom:
I’d not give up fighting without bloodshed between two forces.

I'd suggested before that this was almost certainly where Geoffrey of Monmouth got his notion of Uther's comet (https://mistshadows.blogspot.com/2020/02/uthers-star-and-comet-of-442-ad.html).  In fact, Geoffrey has Merlin pronounce to the king: "the star, and the fiery dragon under it, signifies yourself."  Of course, he also took gorlassar and converted the epithet for Uther himself into Gorlois, Duke of Cornwall. In reality, Uther was referring to himself as the 'cannwyll' when he used gorlassar, so in this sense gorlassar is the cannwyll. 

At first glance there would seem to be no possible connection between a transformation into a fox and one into a comet.  Except when we remember that Uther's comet is a tailed comet.

The red fox of Britain can have a coat whose colors mimic those of fire.  He is also known for his remarkably long and bushy tail.  In fact, the Welsh word for fox is llwynog, 'bushy', a reference to the tail.  The English word fox comes from a root meaning 'tail.'  While not attested until late, W. llostog, 'tailed', is also a name for the fox.  And, finally, ser llostog is a tailed star or comet, and ser llosgyrnog is a star (comet) with a long or prominent tail.

Could it be that Uther's comet was not a dragon, but instead was visualized as a fox?  It was gorlassar - radiant, shining, blazing - like a fox's coat, and it had the fox's long, bushy tail.

An intriguing idea.  Alas, we have no evidence that a comet could be perceived, symbolically speaking, as vulpes vulpes by Dark Age Britons.