No matter how many novels and films have dealt with his figure, some in a fantastic tone, others more realistic, it is very difficult to establish King Arthur’s degree of historicity. Some historians consider him to be more myth than anything else, while others believe they see a series of authentic characters that could have inspired this legend. What does seem to be agreed upon is that the first mention and basis for everything is the Battle of Mons Badonicus, fought some time between the 5th and 6th centuries AD.

There are several names of reference when the question of King Arthur is raised. One corresponds to a commander of the Sarmatian cavalry of the Roman army stationed in Britain named Lucius Artorius Castus, although his presence seems perhaps too distant in time, being placed in the second century A.D. Another is King Riothamus, of whom it is not clear whether he was Briton or Breton but who in 468 responded to the call of Emperor Anthemius to join an alliance against the Visigoths of Aquitaine, who had broken their status as foederati. And a third Artúr mac Áedáin, British-Roman prince of Dál Riata (a kingdom roughly extending between western Scotland and northeastern Ireland) in the 6th century AD.

But the most consistent may be Ambrosius Aurelianus, a Celtic-Roman chieftain who stopped the Anglo-Saxon invasion in the 5th century. He did so, according to tradition, in a decisive battle: that of Mons Badonicus, whose location is not even known with precision beyond the fact that it was in Britain. In fact, uncertainty is a constant in this story because we also ignore the exact date on which the clash took place, estimated to be between 490 and 517 AD.

King Arthur in a Romantic Painting by Charles Ernest Butler/Image: public domain on Wikimedia Commons

The most important documentary source available is De Excidio et Conquestu Britanniae (On the Ruin and Conquest of Britain), written by a native cleric named Gildas and consisting of a sermon in which he condemns his contemporaries, both religiously and in terms of customs. Gildas presents his land plunged into misgovernment and corruption since the end of Roman rule and, although his historical references are vague because the tone is mainly moralistic, it is fortunate that he reviews the Battle of Mons Badonicus because it coincides with his birth, in the year 500.

Other sources are the Historia Brittonum (History of the Britons), composed in the ninth century by an unidentified author (the Welsh monk Nennius is suggested but there is no consensus) and consisting of a compilation of various thematic issues, and the Historia Regum Britanniae (History of the Kings of Britain) also written by a cleric, Geoffrey of Monmouth. Both works present King Arthur as real and form the basis of later accounts, as well as alluding to the battle we are discussing.

According to Gildas, Ambrosius Aurelianus -one of the few characters he identifies by name- became the leader of the resistance against the Anglo-Saxon invaders, who had begun to settle on the island. In contrast to the classic vision of them as assailants who violently destroyed the native Briton culture, today it is believed that they migrated in waves and, except for some warlike events, they generally remained as a ruling elite that acculturated the local population, in a similar process to that which the Visigoths or the Muslims initially carried out in the Iberian Peninsula.

Ambrosius Aurelianus was descended from a Roman family, as can be deduced from Gildas’ description that his father “wore purple”; was he therefore a tribune or even a senator? Or did the chromatic allusion refer to blood and should he be interpreted as a martyr? Because he was also a Christian, which must have given him a certain ascendancy over his men. Geoffrey of Monmouth supposes him to be the brother of Uther Pendragon, both sons of King Constantine who have to flee pursued by a warlord called Vortigern, cursed for having been the one who invited the Anglo-Saxons to enter Britain, in a similar role to that of the Visigothic Don Julian in Hispania.

British kingdoms in the 6th century: Britons (in black), Irish (in blue), Picts (in brown) and Germanic (in red)/Image: Briangotts on Wikimedia Commons

The problem is that this author must have confused two characters called Ambrosius, in the same way that he merged Uther and Pendragon, who were in fact two brothers, which was the result of oral tradition, which was still very important at that time. Nor should these accounts be taken at face value, as they always contain erroneous elements; for example, Geoffrey of Monmouth attributes to Ambrosius Aurelianus the construction of Stonehenge as a mausoleum for himself and Uther.

For his part, Nennius also points to the confrontation between Ambrosius and Vortigern (a religious duel, according to some researchers, who see in it the polarity between Catholicism and Pelagianism), whom he defeated and became “king of kings of the British nation”… only we do not know in which part of Britain he reigned. As we have said before, it is all rather ethereal, and the specific account of the Battle of Mons Badonicus is no exception, for not only the place and date are unknown, but also the number of forces involved and the identity of the generals on both sides present.

Whether it was Ambrosius Aurelianus or King Arthur who commanded the Roman-British, either directly or by delegating subordinates, it seems that his forces took up positions on that hill. They were cosmopolitan, comprising some island cohorts but also a contingent of Sarmatian cavalry; the Sarmatians, with their drachms in the wind, were Iranian mercenaries whom the Romans recruited for their ability to fight on horseback but who, unlike their Scythian kinsmen, fought as heavy horsemen, with spear and scale armour, technically called cataphracts.

Opposing him was the army of Ælle, the first king of the South Saxons, founder of the kingdom of Sussex, whose existence, like everything else, is doubtful. According to the Anglo-Saxon Chronicle, Ælle landed at Cape Selsey Bill from Germania, defeated the Britons and colonised the region with his people, becoming a Bretwalda, a sort of primus inter pares of the various monarchs of the Anglo-Saxon groups. For his was not the only wave of outsiders, for Britannia was also under attack from Angles, Jutes and Frisians, taking advantage of the fact that Rome had gone and ignored the Britons’ plea for help.

The Saxon King Ælle in a 17th century illustration/Image: public domain on Wikimedia Commons

The Historia ecclesiastica gentis Anglorum (Ecclesiastical History of the People of the Angles) which Bede the Venerable wrote in 731, and the aforementioned Anglo-Saxon Chronicle are the references we have to Ælle by name but give little more information except that he was not a Christian and some accounts of battles. One of these was Mons Badonicus, which Bede says was forty-four years after the first Anglo-Saxon settlement in Britain, which would have coincided with the Roman emperors Marcian and Valentinian, between 449 and 456, so the battle must have been between 493 and 500.

Unfortunately, Bede did not leave an account of the battle. Gildas did, speaking of a “great slaughter” that allowed the “unexpected recovery of the island” and granted a period of peace lasting four decades. Despite their huge numerical inferiority, the British forces were able to use their better position, protected by the hill and the Avon River, to resist the enemy’s charges until the Sarmatian cavalry arrived by surprise and attacked the enemy’s flank.

The Historia Brittorum recounts that Ælle lost nearly a thousand men, most of them personally felled by a warrior named Arthur; it is the earliest extant mention of King Arthur but is dated much later, in the 9th century. Gildas says nothing about him, but scholars think that he may have considered it unnecessary as it was already a popular story, assuming that everyone knew that it was Arthur who led the Britons. The Annales Cambriae or Annals of Wales (from the late 10th century) also attribute him to being the protagonist, thanks to the fact that he carried a banner with the cross of Christ or an image of the Virgin.

Geoffrey of Monmouth’s Regum Britanniae adds other familiar names, such as Merlin – who predicted that the Badon baths would become poisonous to the Anglo-Saxons – or the sword Caliburnus (Caliburn, Excalibur) and the spear Ron, as well as reducing the number of Arthur’s victims to “only” half. Indeed, there are a multitude of place and battle names linked to the Arthurian myths that scholars have tried to identify and locate; Mons Badonicus is, of course, one of them.

And the list of candidates is not short. Others include Bowden Hill (Linlithgow), Mynydd Baedan (South Wales), Badbury Rings (an Iron Age fortress in Dorset), Solisbury Hill (a spot near the city of Bath suggested by Godfrey of Mounmoth), Buxton (a hill near the Roman Baths in Derbyshire), Liddington Castle (Wiltshire) and Bardon Hill (Leicestershire). It remains a mystery to this day.

This post was first published on our Spanish Edition on February 4, 2019. Este artículo también está disponible en español: La Batalla del Monte Badon, primera referencia documental al rey Arturo


Gildas, De Excidio et Conquestu Britanniae | Nennius, History of the Britons (Historia Brittonium) | Geoffrey of Monmouth, Historia Regum Britanniae | Bede, Historia eclesiástica del pueblo de los anglos (Historia ecclesiastica gentis Anglorum) | Michael Swanton, ed., Anglo-Saxon Chronicle | John Williams, ed., Annales Cambriae | Rodney Castleden, King Arthur. The truth behind the legend | Geoffrey Ashe, Merlín. Historia y leyenda de la Inglaterra del rey Arturo | Frank E. Reno, The historic king Arthur. Authenticating the celtic hero of post-Roman Britain | Wikipedia

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