The genesis of a  historic King Arthur in Britain precedes Geoffrey of Monmouth’s “Arthur of Britain” by nine and a half centuries.  Researched thoroughly by C. Scott Littleton and Linda Malcor, there is overwhelming evidence that a Roman commander named Lucius Artorius Castus was deployed to Britain near the end of the second century with 5,500 Sarmatian cavalry posted in garrisons along Hadrian’s Wall.  Undoubtedly, the name Arthur is a cognate of Artorius;  he was not a king, but held the important position equivalent to a dux.

    The name “Arthur” does not reappear in British history until the bard Aneirin, at the beginning of the seventh century, wrote a lament about a fierce battle in which a northern British chieftain named  Gwarwrddur “glutted black ravens on the ramparts, but he was no Arthur”, a poetic style meaning that the Celtic chieftain killed many enemies, but he was not as distinguished as Arthur. That terse reference to Arthur has corrupted British history for over a millennium.

     Gildas of the sixth century, and Bede of the eighth century make make no mention of a British King Arthur, nor of a historic Arthur of the fifth century.  It is Nennius–a copyist of British history  of the ninth century–who finally records the name of Arthur and a list of Arthur’s twelve battles.  The pervasive tragedy is that Nennius sets Arthur in the fifth century, fighting against the invading Saxons.  And even more catastrophic, Geoffrey of Monmouth in the twelfth century accepted Nennius’s material as authentic history, and created–inadvertently or perhaps intentionally–a monumental distortion of a historic King Arthur set in the fifth century.

     Monmouth’s genealogical errors  must be rectified.  He not only conflated Artorius Castus of the second century with a bonafide king of the fifth century named Ambrosius Aurelianus, but also relegated Ambrosius to a minor role.    Arthur likewise had no father named Utherpendragon or a grandfather named Constantine who was a “king of Britain;” no doubt Constantine the Usurper was conflated with Constantius III of that era.  Emending those misconceptions, there is no historic King Arthur of the fifth century, nor does history record the name of Utherpendragon as Ambrosius’s brother.  Ambrosius Aurelianus, son of   Constantius III, must be recognized as the “great king of all the kings of Britain,” as recorded in the Historia Brittonum.