The Visigoths famously sacked Rome in 410 under their King, Alaric. This was but one in a long list of conflicts where roman and Visigoth troops had fought. Sometimes together, as the Visigoths were at first foederati of the Empire. Then against, as the Visigoths rebelled after tension with their Roman overlords.
Alaric was King, but he was not the only chieftain, and such men would form part of the command of Visigoth armies.