"Now other Roman soldiers, also, had been stationed at the frontiers of Gaul to serve as guards. And these soldiers, having no means of returning to Rome, and at the same time being unwilling to yield to their enemy who were Arians, gave themselves, together with their military standards and the land which they had long been guarding for the Romans, to the Armoricans and Franks; and they handed down to their offspring all the customs of their fathers, which were thus preserved, and this people has held them in sufficient reverence to guard them even up to my time. For even at the present day they are clearly recognized as belonging to the legions to which they were assigned when they served in ancient times, and they always carry their own standards when they enter battle, and always follow the customs of their fathers. And they preserve the dress of the Romans in every particular, even as regards their shoes." – History of the Wars XII
A few things stand out from this passage:
1. These troops were respected by the Armoricans and Franks. They were not half-trained levys or barbarian mercenaries. They were soldiers of sufficient quality to impress not only the Gallo-roman inhabitants of northern Gaul (the Armoricans or 'Arborychi' as Procopius misspelt it) but also the Frankish conquerors who took over that region. The Franks held them in such high regard that they did not disband them but accepted their fealty. Quality troops indeed.
2. They were professional soldiers in the Roman tradition. Their metier was passed from father to son, i.e. it was a traditional occupation that was handed down in a family, as was customary with many Roman professions in that time. These men made soldiering a lifelong career, with all the pride and competence that went with it.
3. They were proud of being Roman. They made it clear that they were Roman soldiers, by the standards they took into battle, the military traditions they kept, even the uniforms they wore. This sense of Roman identity was remarkable, and enabled them to remain in being nearly a century after the deposition of the last Roman emperor in 476.
It was these troops that held Clovis and his Franks at bay for ten years, something that no other of his enemies was able to do. Their resistance ceased only when Clovis was baptized at Reims in 496/7, making him a ruler the Catholic inhabitants of Armorica could accept. A truly unique performance.