Riothamus is one of the few 100% historically rooted Brythonic figures from the 5th century. While we can generally trust that many of the figures I’ve discussed here were historic, Riothamus is definitely historical. He has become ever present in the discussion of Arthuriana as part of the inspiration for the later composite Arthur, so naturally I would have to address this and discuss Riothamus at some point.
The Sources
Sidonius
Unlike many of these figures we have a contemporary mention of him in a letter from Sidonius Apollinaris
To his friend Riothamus
I will write once more in my usual strain, mingling compliment with grievance. Not that I at all desire to follow up the first words of greeting with disagreeable subjects, but things seem to be always happening which a man of my order and in my position can neither mention without unpleasantness, nor pass over without neglect of duty. Yet I do my best to remember the burdensome and delicate sense of honour which makes you so ready to blush for others' faults. The bearer of this is an obscure and humble person, so harmless, insignificant, and helpless that he seems to invite his own discomfiture; his grievance is that the Bretons are secretly enticing his slaves away. Whether his indictment is a true one, I cannot say; but if you can only confront the parties and decide the matter on its merits, I think the unfortunate man may be able to make good his charge, if indeed a stranger from the country unarmed, abject and impecunious to boot, has ever a chance of a fair or kindly hearing against adversaries with all the advantages he lacks, arms, astuteness, turbulences, and the aggressive spirit of men backed by numerous friends. Farewell
This letter, while lacking major information on the man gives us two things, first that he held power over the Bretons, and two that he was a contemporary of Sidonius and has a Floruit beginning before 485, Sidonius’ death.
Jordanes
The next source to mention him is The Origin and Deeds of the Goths by Jordanes, written around 551a.d.
Now Euric, king of the Visigoths, perceived the frequent change of Roman Emperors and strove to hold Gaul by his own right. The Emperor Anthemius heard of it and asked the Brittones for aid. Their King Riotimus came with twelve thousand men into the state of the Bituriges by the way of Ocean, and was received as he disembarked from his ships. Euric, king of the Visigoths, came against them with an innumerable army, and after a long fight he routed Riotimus, King of the Britons, before the Romans could join him. So when he had lost a great part of his army, he fled with all the men he could gather together, and came to the Burgundians, a neighboring tribe then allied to the Romans. But Euric, king of the Visigoths, seized the Gallic city of Arvernum; for the Emperor Anthemius was now dead.
With Jordanes information provided we can then fine tune when Riothamus was operating, as it must have started before Anthemius’ death in 472. roughly While it would seem that Sidonius insinuates that he was a King over the Bretons, Jordanes calls him the less specific “King of the Britons” and says he brought twelve thousand “by the way of the Ocean”. While this may seem to mean that Riothamus crossed the channel from Britain, it is equally possible that it was easier for him to transport troops up the coast from wherever his seat of power was in Armorica by the sea. This does however open up a possibility that he and Ambrosius Aurelianus are actually the same figure. Both being called 'King of the Britons’ after Vortigern and being roughly contemporaneous. It is possible that the “high-kingship” in Britain at the time included power over Armorica as well. This would imply that Riothamus was not a personal name, but a title, which clashes with earlier letter from Sidonius, although it may have been a nom de guerre that became common use for the man even in his lifetime.
Sidonius’ letter to Vincentius
While nothing more from the period addresses Riothamus directly, there may be an indirect reference to his military force, mentioned in intercepted correspondence between the Praetorian prefect of Gaul Arvandus, and the King of the Visigoths, Euric.
They brought, with other matters entrusted to them by the province, an intercepted letter, which Arvandus' secretary, now also under arrest, declared to have been dictated by his master. It was evidently addressed to the King of the Goths, whom it dissuaded from concluding peace with 'the Greek Emperor', urging that instead he should attack the Bretons north of the Loire, and asserting that the law of nations called for a division of Gaul between Visigoth and Burgundian.
Geoffrey Ashe takes these “Bretons north of the Loire” to be Riothamus and his forces, and paints Arvandus letter as a betrayal ala Mordred. After the apprehension of the letter Arvandus was recalled to Rome, was subsequently put on trial and found guilty. While this letter does not directly link Riothamus and Arvandus it certainly seems to line all the pieces up perfectly.
Riothamus comes to Emperor Anthemius’ aid, Arvandus warns Euric, Euric cuts Riothamus off and deals him a massive defeat. The one thing that doesn’t line up here is that if Sidonius and Riothamus were well acquainted as the letter between the two suggests, it would be strange to not mention Riothamus’ defeat in his letter to Vincentius. This does pose a problem for this interpretation in my opinion, and makes it more likely that these are separate incidents, and Riothamus’ defeat at the hands of Euric was likely after letter from Arvandus to Euric, and instead of meaning to cut off Riothamus from coming to Anthemius’ aid instead it was to further divide the empire by stirring up trouble.
Riothamus as Arthur
Many have noted similarities between Riothamus and especially Geoffrey of Monmouth’s rendition of Arthur (who as I discuss before is a composite figure where it overlaps with history, but is generally ahistorical). These are generally proposed as his position of “King of the Britons”, his military action in Gaul, as well as his supposed betrayal at the hands of Arvandus.
We have touched on the holes with the ‘betrayal’ of Arvandus, but what of the other two points? First the ‘King of the Britons’ connection. In the period that Riothamus was operating the ‘King of the Britons’ was either Vortigern late in his reign, or Ambrosius during his. So either Riothamus was Ambrosius successor if we are to take this as the position of ‘High King’ which would align with Geoffrey’s contention that Arthur was High King after Ambrosius, but also shifts Riothamus further out of sync. If this was truly one single title ‘High King of the Britons’ then Riothamus is more likely to be Ambrosius than he is Arthur as I have mentioned before. This brings us to the military action in Gaul. I will concede that this easily could be true, and as such could be the contribution of Riothamus to the later composite Arthur, however, it is as likely that this was inspired by tales of Magnus Maximus, who is heavily remembered in Brythonic legend, and his continental campaigns more likely account for the later interpretation by Geoffrey of Monmouth that Arthur fought the Romans, defeated them, and became Emperor.
A Small Point of Potential for Riothamus as Ambrosius
There is another bit of potential evidence within Gildas. Gildas mentions that Ambrosius descendants had “become greatly inferior to their grandfather's excellence” while we don’t have confirmation from Gildas who exactly these descendants were, we might have clues from Gildas himself. One of the Kings he mentions is Aurelius Caninus, a curious connection of names there. If Aurelius Caninus is a descendant of Ambrosius, who may he actually have been? While it has been suggested that it Caninus is Cynan Garwyn, this is unlikely as his pedigree shows descent from Vortigern. It could be that Aurelius Caninus (Little-Dog) is possibly Conomor of the Domnonée who is similarly remembered as being an evil man. If this is Ambrosius’ descendent, maybe there is a stronger case that Riothamus and Ambrosius were possibly the same man. Sadly there isn’t much room for confirmation here so we are subject to the realm of conjecture.
Maybe, Maybe Not
While Riothamus is a fascinating figure, and can easily be molded to fit a “Proto-Arthur” it requires a significant amount of stretching to say “This was THE Arthur”. While it is always possible that the inspiration for the later Composite Arthur’s Gallic Campaigns came from Riothamus, they easily can be explained in other ways, however he still remains a valuable insight into the period, and possibly gives more precedent to a wider Brythonic ‘High King’ within the realm of real history.
Do you have a recommended 1 - 3 books as key introductions to the Arthurian legends, ideally that give both background context but are exciting and romantic enough that they also build enthusiasm to learn more?