According to Grote, King Theoderic I was the son of King Walia but Wolfram says that nothing is known about the earlier life of Theoderic.
He was elected to succeed in 418 as THEODERIC I King of the Visigoths. Olympiodorus Thebæus records the death of “Valia, principe Gothorum”, and the succession of “Theuderichus”. Iordanes names "Theoderidum" as successor of "Vallia rex Gothorum" but does not specify any relationship between the two. He completed the transfer of Visigothic activity from Spain to France based on Toulouse. In 422, the Visigoths marched against the Vandals in Spain but deserted their Roman allies who suffered a serious defeat. The Visigoths became more aggressive in their raids against Roman towns in Gaul, besieging Arles several times between 425 and 430, and Narbonne in 437. The Romans counter-attacked Toulouse in 439, although their leader Litorius was killed. The Visigoths fought for the Romans against the Suevi in Spain in 446, but made an alliance with the latter in 449, confirmed by the marriage of Theoderic’s daughter to the Suevi king. King Theoderic marched with his two eldest sons into Champagne in summer 451 against Attila the Hun.
He was killed in the battle of the Catalaunian fields in which the combined Roman/Visigothic forces defeated the Huns. Iordanes records that he was killed "in campis statim Catalaunicisis". Gregory of Tours records that Theoderic King of the Goths was killed in battle against Attila in support of his allies the Franks.
The Chronica Regum Visigotthorum records that “Theuderedus” reigned for 33 years. 1
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