28 (return) [ Appian of Alexandria, in the preface to his History of the Roman Wars.] The terror of the Roman arms added weight and dignity to the moderation of the emperors. They preserved peace by a constant preparation for war; and while justice regulated their conduct, they announced to the nations on their confines, that they were as little disposed to endure, as to offer an injury. The military strength, which it had been sufficient for Hadrian and the elder Antoninus to display, was exerted against the Parthians and the Germans by the emperor Marcus. The hostilities of the barbarians provoked the resentment of that philosophic monarch, and, in the prosecution of a just defence, Marcus and his generals obtained many signal victories, both on the Euphrates and on the Danube. 29 The military establishment of the Roman empire, which thus assured either its tranquillity or success, will now become the proper and important object of our attention. 29 (return) [ Dion, l. lxxi. Hist. August. in Marco. The Parthian victories gave birth to a crowd of contemptible historians, whose memory has been rescued from oblivion and exposed to ridicule, in a very lively piece of criticism of Lucian.] In the purer ages of the commonwealth, the use of arms was reserved for those ranks of citizens who had a country to love, a property to defend, and some share in enacting those laws, which it was their interest as well as duty to maintain. But in proportion as the public freedom was lost in extent of conquest, war was gradually improved into an art, and degraded into a trade. 30 The legions themselves, even at the time when they were recruited in the most distant provinces, were supposed to consist of Roman citizens. That distinction was generally considered, either as a legal qualification or as a proper recompense for the soldier; but a more serious regard was paid to the essential merit of age, strength, and military stature. 31 In all levies, a just preference was given to the climates of the North over those of the South: the race of men born to the exercise of arms was sought for in the country rather than in cities; and it was very reasonably presumed, that the hardy occupations of smiths, carpenters, and huntsmen, would supply more vigor and resolution than the sedentary trades which are employed in the service of luxury. 32 After every qualification of property had been laid aside, the armies of the Roman emperors were still commanded, for the most part, by officers of liberal birth and education; but the common soldiers, like the mercenary troops of modern Europe, were drawn from the meanest, and very frequently from the most profligate, of mankind.