Was Riothamus the Real King Arthur?

Riothamus was a historical figure who is often claimed to be the real King Arthur. Do the available historical facts really support this conclusion?

Jun 23, 2024By Caleb Howells, BA Doctrines and Methodology of Education

was riothamus real king arthur


The legends of King Arthur have inspired speculation for centuries. These legends originate from early Dark Age Britain, from which we have very few surviving sources. There is no direct confirmation of the existence of a real King Arthur. However, that does not mean that we are completely devoid of knowledge about historical figures from that era. Some researchers attempt to “confirm” Arthur’s existence by identifying him with a differently-named figure whose historicity is confirmed. One such individual is Riothamus, a king of the Britons who was active in the second half of the 5th century.


Who Was Riothamus, the “Real King Arthur”?

Euric, King of the Visigoths, by John Chapman, 1807, Source: Scottish National Portrait Gallery, Scotland


Firstly, let us establish who Riothamus was. He appears in two surviving sources from the early Dark Ages, though neither source is from Britain. One of them is a letter from Sidonius Apollinaris, the bishop of Clermont. In this letter, Sidonius writes to Riothamus on behalf of a poor citizen of the land, who claims that some Britons are taking his slaves away. He appeals to Riothamus to resolve this situation. This would suggest that Riothamus had authority over the Britons.


The other source that mentions Riothamus is the 6th-century historian Jordanes. In his account of the Visigothic wars in Gaul, led by King Euric, Jordanes explains that Western Roman Emperor Anthemius appealed to the Britons for help in about 470. The account says that King Riothamus “came with twelve thousand men into the state of the Bituriges by the way of the ocean.” He then fought against Euric. The Visigothic leader was victorious and caused Riothamus and his Brittonic army to flee. Jordanes tells us that Riothamus fled to the Burgundians, a neighboring people who were allied to the Romans.


Why Some Believe Riothamus Was the Real King Arthur

Illustration of King Arthur in battle, 13th century, Source: Pocketmags


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With this information in mind, why do some scholars believe that Riothamus was the historical figure behind the legends of King Arthur? After all, in the Arthurian legends, he is not just presented as a military leader who fought against the Saxons in Britain.


In c. 1137, Geoffrey of Monmouth wrote the Historia Regum Britanniae, which added a major part to the legend. He described Arthur as traveling across to Gaul to conquer a large part of the Western Roman Empire. Over the course of several years, Arthur conquered that territory and then eventually fought an enormous battle against the Romans and a coalition of other nations. Riothamus is the only historical person recorded as “king of the Britons” who traveled with an army to Gaul in the Arthurian period. Therefore, this makes him an obvious candidate for the inspiration of at least this part of the legend. Furthermore, “Riothamus” might be a title meaning “Highest King.” In the 20th century, Historian Geoffrey Ashe pushed heavily for the identification of Riothamus with Arthur, and the theory has become quite popular since then.


Bust of Roman Emperor Leo I, 470 CE, Wikimedia Commons


In addition, several characters from the legends can supposedly be identified with historical figures from this period. One supposed link is the Roman Emperor of the Arthurian legend, called Lucius. He has been connected to Roman Emperor Glycerius. Another emperor mentioned is Emperor Leo, who would appear to match the historical Emperor Leo I. The Arthurian account also mentions a pope named Supplicius, a supposed match for Pope Simplicius. Furthermore, Ashe argues that Riothamus was betrayed by a person named Arvandus. Supposedly, this would match the fact that King Arthur was said to have been betrayed by Mordred, his nephew.


Another reason why some believe that Riothamus was the real King Arthur is related to the fact that Riothamus fled to the territory of the Burgundians after his defeat. Advocates of this theory point out that a nearby city in their territory was called Avallon. Thus, Riothamus may well have fled to that city in particular, which could be the origin of the legend of Arthur traveling to Avalon after his last battle.


Did Riothamus Really Come From Britain?

Map of Brittany, by Paul Vidal de La Blache, 19th century, Source: Wikimedia Commons


One of the absolute key parts of this theory is that Riothamus came from Britain and traveled to Gaul. However, that is not what Jordanes actually says. What he says is that Riothamus arrived in “the state of the Bituriges by way of the ocean.” This has been taken to confirm that Riothamus came from across the sea, from Britain. However, Jordanes does not say that he “crossed” the ocean, just that he came “by way of the ocean.”  Nor does it say that he arrived in Gaul by that means, but that he arrived in the state of the Bituriges, a specific area in Gaul.


We know that Britons had already settled in the northwest corner of Gaul by Riothamus’ time. Their territory later became Brittany, and these Britons became the Bretons. Could Riothamus have actually been a king of these Bretons? If Riothamus had come from Britain, then Jordanes’ reference to him coming by way of the ocean would be redundant, because there is no alternative. On the other hand, if Riothamus was already in Gaul, then this statement is logical because it provides some useful information to the reader.


The Dissimilarities Between Riothamus and King Arthur

Illustration of King Arthur fighting the Saxons, from the Rochefoucauld Grail manuscript, 14th century, Source: The Independent


Another issue with identifying Riothamus as the real King Arthur is that their activities are completely dissimilar. Even if we accept that Riothamus did come from Britain, which seems unlikely, his subsequent actions do not match Arthur’s at all. King Arthur was said to have been incredibly successful, conquering huge portions of Gaul. On the other hand, Riothamus was entirely unsuccessful in his endeavor. There is no record of him having any military successes in Gaul. Based on the evidence as we actually have it, Riothamus completely fails to match the profile of Arthur. It is more than a little difficult to see how such a defeat could have come to be remembered as a glorious conquest.


Additionally, Riothamus was an ally of the Romans. In contrast, the Romans were Arthur’s enemy during his legendary conquest of Gaul. So not only do the events themselves not match the Arthurian legend, but the surrounding historical context also does not match.


Misidentifications of Arthurian Characters

King Arthur Tapestry, c. 1385, Source: Wikimedia Commons


This theory depends greatly on the supposed matches between historical figures and characters from the Arthurian legends. While the match between Emperor Leo and the historical emperor by that name appears reasonable enough, the other matches do not stand up to scrutiny. Regarding the identification of Emperor Lucius with Emperor Glycerius, this depends on the Chronicle of Sigebert of Gembloux. It calls Glycerius “Lucerius” and mistakenly places his reign in 469-470, whereas he actually ruled a few years later, after Riothamus’ defeat. For Geoffrey of Monmouth to have used the information in this chronicle for his account, he must have believed that Arthur was active in the 5th century. Yet, he explicitly places Arthur’s death (not long after his European campaign) in the year 542. Furthermore, the idea that Lucius in the Arthurian legend was an emperor is incorrect. He is never called an emperor in the account, but only a procurator and commander.


Pope Supplicius, for his part, appears in the account simply as the teacher of Walgan (more famously known as Gawain). Walgan was the nephew of Urien Rheged, a historical figure of the late 6th century. Therefore, Supplicius must have been a 6th-century figure, not the 5th-century Simplicius. Most likely, he can be identified with Pope Pelagius I.


The Death of Arthur and Mordred, by N. C. Wyeth, 1922, Source: Wikimedia Commons


The supposed connection between Arvandus the Roman Prefect of Gaul and the Arthurian Mordred is also unconvincing. Supposedly, Arvandus betrayed Riothamus by telling Euric to attack the Britons situated beyond the Loire. However, this bears no relation to the legend of Mordred. He was Arthur’s nephew and a loyal ally, but then he rebelled against Arthur and usurped the throne while Arthur was away in Gaul. The two “betrayals” bear no similarity to each other whatsoever. In fact, it would be strenuous to even describe Arvandus as “betraying” Riothamus at all, since they had no connection with each other. Additionally, Mordred’s betrayal led to the Battle of Camlann in Britain, which is explicitly a separate battle from the ones that occurred in Gaul.


The identification of the city of Avallon with the Arthurian Avalon also does not stand up to scrutiny. The Arthurian Avalon is an island in the western ocean. It is not a city. Furthermore, Arthur goes there after the Battle of Camlann, not after the battle against the Romans.


Can Riothamus Be Identified as the Real King Arthur?

Replica of King Arthur’s Round Table, 13th century, Winchester, England, Source: Historic-uk


With all of this information in mind, can Riothamus really be identified as the real King Arthur? Historically, what we know about Riothamus is that he was the king of the Britons in the second half of the 5th century. As an ally of the Romans, he fought against the Visigoths and lost. Every aspect of his life is different from the activities of Arthur in the Arthurian legends. According to those legends, Arthur fought against the Romans and successfully conquered a large portion of Western Europe.


In fact, it is likely the case that Riothamus did not even come from Britain. Jordanes’ statement about him arriving by way of the ocean would be redundant if he had come from Britain. Therefore, it is more likely that he came from Brittany in northwest Gaul. While it is true that the match between the Emperor Leo of the legend and the historical Emperor Leo I is plausible, none of the other matches work. They all collapse when the issue of chronology is examined. And while ‘Riothamus’ could potentially be a title, its usage in Sidonius’ letter makes this very unlikely. In conclusion, there is no good case to be made that Riothamus was the real King Arthur.

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By Caleb HowellsBA Doctrines and Methodology of EducationCaleb is a published history author with a strong interest in ancient Britain and the Mediterranean world. He holds a BA in the Doctrines and Methodology of Education from USILACS. He is the author of "King Arthur: The Man Who Conquered Europe" and "The Trojan Kings of Britain: Myth or History?". Caleb enjoys learning about history in general, but he especially loves investigating myths and legends and seeing how they might be explained by historical events and individuals.