This unceasing emigration gradually changed the character of the rural population, and a similar alteration took place in the army. As early as the time of Cæsar, Italy was exhausted; his legions were mainly raised in Gaul, and as the native farmers sank into serfdom or slavery, and then at last vanished, recruits were drawn more and more from beyond the limits of the Empire. At first they were taken singly, afterwards in tribes and nations, so that, when Aëtius defeated Attila at Châlons, the battle was fought by the Visigoths under Theodoric, and the equipment of the Romans and Huns was so similar that when drawn up the lines “presented the image of civil war.” This military metamorphosis indicated the extinction of the martial type, and it extended throughout society. Rome not only failed to breed the common soldier, she also failed to produce generals. After the first century, the change was marked. Trajan was a Spaniard, Septimius Severus an African, Aurelian an Illyrian peasant, Diocletian a Dalmatian slave, Constantius Chlorus a Dardanian noble, and the son of Constantius, by a Dacian woman, was the great Constantine. All these men were a peculiar species of military adventurer, for they combined qualities which made them, not only effective chiefs of police, but acceptable as heads of the civil bureaucracy, which represented capital. Severus was the type, and Severus has never been better described than by Machiavelli, who said he united the ferocity of the lion to the cunning of the fox. This bureaucracy was the core of the consolidated mass called the Empire; it was the embodiment of money, the ultimate expression of force, and it recognized and advanced men who were adapted to its needs. When such men were to be found, the administration was thought good; but when no one precisely adapted for the purple appeared, and an ordinary officer had to be hired to keep the peace, friction was apt to follow, and the soldier, even though of the highest ability, was often removed. Both Stilicho and Aëtius were murdered. The monied oligarchy which formed this bureaucracy was a growth as characteristic of the high centralization of the age, as a sacred caste is characteristic of decentralization. Perhaps the capitalistic class of the later Empire has been better understood and appreciated by Fustel de Coulanges than by any other historian. “All the documents which show the spirit of the epoch show that this noblesse was as much honoured by the government as respected by the people.... It was from it that the imperial government chose ordinarily its high functionaries.” These functionaries were not sought among the lower classes. The high offices were not given as a reward of long and faithful service; they belonged by prescriptive right to the great families. The Empire made the wealthy, senators, prætors, consuls, and governors; all dignities, except only the military, were practically hereditary in the opulent class.