Amled,
Sir you are making the same mistake that Gibbon and others made about the Roman Army in the later empire period. It is true that Hannible destroyed Roman army after army and they simply raised new ones, while in the later period (as seen glaringly after Adrianpole) they found it difficult if not impossible to raise troops. But, in the time of Messrs Hannible and Scipio Rome was still a city state, one which could do so. All men were liable for service. But in the later period they were an empire, what more an empire which was now centered largly outside Rome (no longer even the capital) and they could not simply make all men liable for service like they did before. It was not due to a loss of "civic" sence.
Moreover after the "fall" in 476AD the Eastern Empire was able to reconquer large parts of the West, except parts of Iberia, all of Gaul and Britannia, not to mention defeat Persia. True, the Arabs nullified those gains, but the empire was by no means "dead" until then. Great lack of civic sence
. I would say it existed in until the Arab conquests.