The frequent custom of recruiting the legions by means of slaves, in the later period of the empire, which was wholly unknown in the days of the Republic, reveals, in the clearest manner, the weakness to which, in respect of military resources, it had arrived, long before the external symptoms of decay were visible in its fortunes. Even in the time of Marcus Aurelius, the legions which were to combat the Quadi and Marcomanni, on the Danube, were recruited from the servile class. Justinian went so far as to declare, by a public edict, every slave free who had served in the army.[25] "At last the army came to be composed entirely," says Finlay, "of the rudest and most ignorant peasants, of _enfranchised slaves, and naturalised barbarians_. This increased the repugnance, already sufficiently great, felt by the better class of citizens to enter the military life. The mercenaries formed the most valued and brilliant portions of the army, and it became the fashion to copy and admire the dress and manners of the barbarian cavalry."[26]
All the ancient historians concur in representing this impossibility of finding native soldiers in its central provinces, as the main cause of the overthrow of the empire. And that this, and not the power of the barbarians, was the real cause of the destruction of the empire, is proved by the fact, that whenever they were well directed, the superiority of the legions was as clearly evinced as in the days of Marius or Cæsar. "Whenever the invaders," says Finlay, "met with a steady and well-combined resistance, they were defeated without much difficulty. The victorious reigns of Claudius II., Aurelian, and Probus, prove the immense superiority of the Roman armies when properly commanded; but the custom which was constantly gaining ground, _of recruiting the legions from among the barbarians_, reveals the deplorable state of _depopulation and weakness_ to which three centuries of despotism and bad administration had reduced the empire."[27]
But amidst this general prostration of the political and military strength of the Roman empire, in consequence of the decline and desolation of the _country_, the _great towns_ still continued flourishing, and wealth to an extraordinary and unparalleled extent existed among the chief families, some of patrician, some of plebeian origin. That was the grand characteristic of Rome in its later days. The country, in the European part of the empire at least, was daily growing poorer; the cultivation of the fields was neglected; and the provinces, crushed under the weight of the direct taxes, which had become unavoidable, had in most cases sunk to half their former number of inhabitants. But the metropolis, whether in Italy or on the shores of the Bosphorus, was still the seat of opulence, luxury, and prosperity. The strength of Constantinople was sufficient to repel the barbarians, and prolong the life of the empire of the east, for many centuries after it had ceased to derive effective support from any of its provinces. It is recorded by Ammianus Marcellinus, that when Rome was taken by the Goths under Alaric, it was still inhabited by 1,200,000 souls, who were maintained chiefly by the expenditure of seventeen hundred and sixty great families, many of whom had £160,000 of yearly income, equal to at least £300,000 a-year of our money.[28] And of the flourishing condition of the cities of the empire, especially those which were on the shores of the Mediterranean, even so late as the eighth century, Mr Finlay gives the following account:--