As the reign of Diocletian was more illustrious than that of any of his predecessors, so was his birth more abject and obscure. The strong claims of merit and of violence had frequently superseded the ideal prerogatives of nobility; but a distinct line of separation was hitherto preserved between the free and the servile part of mankind. The parents of Diocletian had been slaves in the house of Anulinus, a Roman senator; nor was he himself distinguished by any other name than that which he derived from a small town in Dalmatia, from whence his mother deduced her origin. 1 It is, however, probable that his father obtained the freedom of the family, and that he soon acquired an office of scribe, which was commonly exercised by persons of his condition. 2 Favorable oracles, or rather the consciousness of superior merit, prompted his aspiring son to pursue the profession of arms and the hopes of fortune; and it would be extremely curious to observe the gradation of arts and accidents which enabled him in the end to fulfil those oracles, and to display that merit to the world. Diocletian was successively promoted to the government of Maesia, the honors of the consulship, and the important command of the guards of the palace. He distinguished his abilities in the Persian war; and after the death of Numerian, the slave, by the confession and judgment of his rivals, was declared the most worthy of the Imperial throne. The malice of religious zeal, whilst it arraigns the savage fierceness of his colleague Maximian, has affected to cast suspicions on the personal courage of the emperor Diocletian. 3 It would not be easy to persuade us of the cowardice of a soldier of fortune, who acquired and preserved the esteem of the legions as well as the favor of so many warlike princes. Yet even calumny is sagacious enough to discover and to attack the most vulnerable part. The valor of Diocletian was never found inadequate to his duty, or to the occasion; but he appears not to have possessed the daring and generous spirit of a hero, who courts danger and fame, disdains artifice, and boldly challenges the allegiance of his equals. His abilities were useful rather than splendid; a vigorous mind, improved by the experience and study of mankind; dexterity and application in business; a judicious mixture of liberality and economy, of mildness and rigor; profound dissimulation, under the disguise of military frankness; steadiness to pursue his ends; flexibility to vary his means; and, above all, the great art of submitting his own passions, as well as those of others, to the interest of his ambition, and of coloring his ambition with the most specious pretences of justice and public utility. Like Augustus, Diocletian may be considered as the founder of a new empire. Like the adopted son of Caesar, he was distinguished as a statesman rather than as a warrior; nor did either of those princes employ force, whenever their purpose could be effected by policy.
The victory of Diocletian was remarkable for its singular mildness. A people accustomed to applaud the clemency of the conqueror, if the usual punishments of death, exile, and confiscation, were inflicted with any degree of temper and equity, beheld, with the most pleasing astonishment, a civil war, the flames of which were extinguished in the field of battle. Diocletian received into his confidence Aristobulus, the principal minister of the house of Carus, respected the lives, the fortunes, and the dignity, of his adversaries, and even continued in their respective stations the greater number of the servants of Carinus. 4 It is not improbable that motives of prudence might assist the humanity of the artful Dalmatian; of these servants, many had purchased his favor by secret treachery; in others, he esteemed their grateful fidelity to an unfortunate master. The discerning judgment of Aurelian, of Probus, and of Carus, had filled the several departments of the state and army with officers of approved merit, whose removal would have injured the public service, without promoting the interest of his successor. Such a conduct, however, displayed to the Roman world the fairest prospect of the new reign, and the emperor affected to confirm this favorable prepossession, by declaring, that, among all the virtues of his predecessors, he was the most ambitious of imitating the humane philosophy of Marcus Antoninus. 5
The first considerable action of his reign seemed to evince his sincerity as well as his moderation. After the example of Marcus, he gave himself a colleague in the person of Maximian, on whom he bestowed at first the title of Caesar, and afterwards that of Augustus. 6 But the motives of his conduct, as well as the object of his choice, were of a very different nature from those of his admired predecessor. By investing a luxurious youth with the honors of the purple, Marcus had discharged a debt of private gratitude, at the expense, indeed, of the happiness of the state. By associating a friend and a fellow-soldier to the labors of government, Diocletian, in a time of public danger, provided for the defence both of the East and of the West. Maximian was born a peasant, and, like Aurelian, in the territory of Sirmium. Ignorant of letters, 7 careless of laws, the rusticity of his appearance and manners still betrayed in the most elevated fortune the meanness of his extraction. War was the only art which he professed. In a long course of service, he had distinguished himself on every frontier of the empire; and though his military talents were formed to obey rather than to command, though, perhaps, he never attained the skill of a consummate general, he was capable, by his valor, constancy, and experience, of executing the most arduous undertakings. Nor were the vices of Maximian less useful to his benefactor. Insensible to pity, and fearless of consequences, he was the ready instrument of every act of cruelty which the policy of that artful prince might at once suggest and disclaim. As soon as a bloody sacrifice had been offered to prudence or to revenge, Diocletian, by his seasonable intercession, saved the remaining few whom he had never designed to punish, gently censured the severity of his stern colleague, and enjoyed the comparison of a golden and an iron age, which was universally applied to their opposite maxims of government. Notwithstanding the difference of their characters, the two emperors maintained, on the throne, that friendship which they had contracted in a private station. The haughty, turbulent spirit of Maximian, so fatal, afterwards, to himself and to the public peace, was accustomed to respect the genius of Diocletian, and confessed the ascendant of reason over brutal violence. 8 From a motive either of pride or superstition, the two emperors assumed the titles, the one of Jovius, the other of Herculius. Whilst the motion of the world (such was the language of their venal orators) was maintained by the all-seeing wisdom of Jupiter, the invincible arm of Hercules purged the earth from monsters and tyrants. 9
But even the omnipotence of Jovius and Herculius was insufficient to sustain the weight of the public administration. The prudence of Diocletian discovered that the empire, assailed on every side by the barbarians, required on every side the presence of a great army, and of an emperor. With this view, he resolved once more to divide his unwieldy power, and with the inferior title of Caesars, * to confer on two generals of approved merit an unequal share of the sovereign authority. 10 Galerius, surnamed Armentarius, from his original profession of a herdsman, and Constantius, who from his pale complexion had acquired the denomination of Chlorus, 11 were the two persons invested with the second honors of the Imperial purple. In describing the country, extraction, and manners of Herculius, we have already delineated those of Galerius, who was often, and not improperly, styled the younger Maximian, though, in many instances both of virtue and ability, he appears to have possessed a manifest superiority over the elder. The birth of Constantius was less obscure than that of his colleagues. Eutropius, his father, was one of the most considerable nobles of Dardania, and his mother was the niece of the emperor Claudius. 12