Riothamus

Riothamus (also spelled Riutimus or Riotimus) was a Romano-British military leader, who was active circa AD 470. He fought against the Goths in alliance with the declining Roman Empire. He is called "King of the Britons" by the 6th-century historian Jordanes, but the extent of his realm is unclear. Riothamus is a Latinization of the Brythonic personal name *Rigotamos, meaning 'king-most', 'supreme king' or 'highest king'. Though it is still a matter of debate, several scholars consider his life to have been one of the possible sources for the King Arthur legend.

It is not clear whether Jordanes' "Britons" refers to the Britons of Great Britain itself, or of Armorica, which was undergoing significant British settlement and later came to be known as Brittany.

The Old Breton name Riatam, which (like Riothamus) is derived from Brittonic *Rigotamos, appears in medieval Breton records (primarily biographies of early Breton saints) as one of the Princes of Domnonée (a coastal region in Brittany which takes its name from Dumnonia in southern Britain). He is identified as a son of Deroch II. For chronological reasons, this Riatam is probably a different individual from Jordanes' Riothamus, who lived earlier.

More secure information is provided by a letter which has survived that was written to Riothamus from Sidonius Apollinaris, bishop of Clermont, who requested his judgment for "an obscure and humble person" who had had his slaves enticed away by a group of armed Bretons. According to C.E.V. Nixon, the letter is evidence that Armorica at this time was becoming "like a magnet to peasants, coloni, slaves and the hard-pressed" as Roman power weakened. Poorer subjects of Rome with no stake in land ownership found Breton territory to be a safe haven from the Goths.

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