Diocletian ( Docles, Diocles, Caius Valerius Diocletianus Jovius ), a.d. 284-305. The acts that make the reign of this emperor memorable in the history of the church belong to its closing years. Had he died before a.d. 303 he would have taken his place among the rulers whose general tolerance helped Christianity to obtain its victory. As it is, his name is identified with the most terrible of its persecutions. For three centuries men reckoned from the commencement of his reign as from the era of martyrs; and the date is still recognized in the Coptic Church as the basis of its chronology.
The earlier years of Diocletian concern us only in connexion with the struggle which came to a head when his work seemed nearly over. Elected by the soldiers in Bithynia at the age of 39, after the murder of Numerian, he was formally installed at Nicomedia. In a.d. 286 he chose Maximian as his colleague, gave him the title first of Caesar and then of Augustus, and sent him to command in the West, while he remained in the East, chiefly at Nicomedia, which he tried to make, by lavish outlay on its buildings, a new capital for the empire. It indicates his intention to uphold the religion of the state that he assumed the surname of Jovius, and gave to his colleague that of Herculius. Among the buildings with which he embellished the various provinces were temples of Zeus, Apollo, Nemesis, Hecate, at Antioch, of Isis and Serapis at Rome, of Isis at Phylae, of Mithras at Vindobona. He consulted haruspices and augurs as to the success of his enterprises, and in more difficult emergencies the oracle of the Milesian Apollo at Branchidae (Lactant. de Mort. Pers. cc. 10, 11).
The appointment of Constantius Chlorus and Galerius in a.d. 293 as Caesars under the two Augusti introduced new elements. Each was called on to prove his loyalty to the system into which he was adopted by a new marriage. Constantius divorced Helena and married Theodora, the step-daughter of Maximian. Galerius, also repudiating his former wife, received the hand of Valeria, the daughter of Diocletian and Prisca. To Constantius was entrusted the government of Gaul and Britain, to Galerius the provinces between the Adriatic and the Euxine. Diocletian kept the provinces of Asia under his own control. Maximian had those of Africa and Italy. The edict of Gallienus, a.d. 259, had placed Christianity in the number of religiones licitae, and there had been no formal persecution since. Diocletian and Maximian began by adopting the same policy; and the martyrdoms which are referred to the earlier years of their reign, like those of St. Maurice and the Theban Legion at Martigny (Octodurum), of St. Victor at Marseilles, of SS. Cosmas and Damian and others in Cilicia, if more than legendary, must be referred to special causes, and not to a general policy of persecution. The somewhat cloudy rhetoric of Eusebius in describing the condition of the church of this time indicates that the last struggle with the old religion could not long be averted. The most trusted and influential eunuchs of the household, Dorotheus and Gorgonius, were avowedly Christians and excused from attending at heathen sacrifices (Eus. viii. 1). Prisca the wife, and Valeria the daughter, of Diocletian were kept back from an open profession of faith; but their absence from all sacrifices made men look on them with suspicion (Lactant. de Mort. Persec. c. 15). The church of Nicomedia was the most conspicuous edifice in the city. The adherents of the old system had good reason for alarm. They saw in every part of the empire an organized society that threatened it with destruction. Symptoms of the coming conflict began before long to shew themselves. Malchus, the disciple of Plotinus (better known as Porphyry), wrote against the religion of the Christians while maintaining a tone of reverence towards Christ Himself, and so became in their eyes their most formidable opponent. Hierocles, first as Vicarius of Bithynia and afterwards, probably, as prefect of Egypt, fought against them with pen and sword, and published Words of a Truth-lover to the Christians , in which Christ was compared with Apollonius of Tyana. Within the imperial circle itself some were impatient of the tolerance of Diocletian. The mother of Galerius, who gave sacrificial banquets almost daily, was annoyed because Christian officers and soldiers refused to come to them. The cases of Maximilian of Theveste, in proconsular Africa, who (a.d. 295) had refused to serve as a soldier and take the military oath, as incompatible with his allegiance to Christ, and of Marcellus (a.d. 298), who at Tingis in Mauritania solemnly renounced his allegiance to the emperor rather than take part in idolatrous festivals, had probably alarmed Galerius himself (Ruinart, Acta Sincera , pp. 309, 312).
Occasions for decisive measures were soon found. Diocletian, who seems to have had a devout belief in divination, had offered sacrifice, and the haruspices were inspecting the entrails of the victim to see what omens were to be found there. The Christian officers and servants of the emperor were present as part of their duty, and satisfied their conscience by making the sign of the cross upon their foreheads. The diviners were, or pretended to be, struck with amazement at the absence, despite repeated sacrifices, of the expected signs. At last they declared their work hindered by the presence of profane persons. The emperor's rage was roused. His personal attendants and the officials in his palace were ordered to sacrifice under penalty of being scourged. Letters were sent to military officers bidding them to compel their soldiers to a like conformity under pain of dismissal. The mother of Galerius urged the emperor on, and found but a feeble resistance. He deprecated the slaughter and wished to confine the edict to servants of his household and soldiers. He would take counsel with his friends and consult the gods. One of the haruspices was accordingly sent to the oracle of the Milesian Apollo at Branchidae. The answer came, not from the priestess only, but, as it were, from the god himself speaking from the recesses of his cave, telling him that the presence of the self-styled "just ones" on the earth made it impossible for the oracles to speak the truth. This turned the scale and the emperor gave way. All he asked for was that bloodshed might, if possible, be avoided. Galerius had wished to condemn to the flames all who refused to sacrifice. After many divinations, the Feast of the Terminalia (Feb. 23) of a.d. 303 was chosen as the fit day for issuing the edict against the new society. At break of day the prefect, attended by officers and secretaries, went to the church of Nicomedia while Diocletian and Galerius watched the proceedings from the palace. The doors were broken open. Search was made for the image of the Christian's God, which they expected to find there. The books were burned, the church sacked. Fear of the fire spreading made Diocletian shrink from burning the church, but a body of pioneers with axes and crowbars razed it in a few hours. Next morning an edict ordained that (1) all churches were to be demolished; (2) all sacred books burnt; (3) all Christian officials stripped of their dignities, and deprived of civil rights, and therefore rendered liable to torture and other outrages; while Christian men who were not officials were to be reduced to slavery. A Christian who tore it down, with the sarcastic exclamation, "More triumphs of Goths and Sarmatians!" was seized, tortured, and burnt alive at a slow fire. Shortly after, a fire broke out in the palace and suspicion fell upon the Christians, notably upon the palace eunuchs. The use made of the occurrence to work upon Diocletian's fears justified the impression of Christian writers that it was a device contrived by Galerius and executed by his slaves. All who were suspected were examined by torture; within a fortnight there was another similar alarm, and now there was no limit to the old man's fury. His wife and daughter were compelled to free themselves from suspicion by joining in sacrifice. The eunuchs of his household, before so trusted, Dorotheus, Gorgonius, Petrus, were put to death. The persecution raged throughout the province. Some were burnt, some drowned, some thrust into dungeons. Altars were set up in every court of justice, and both parties to suits compelled to sacrifice. A second edict ordered that all the clergy, without option of sacrifice, should be imprisoned. Anthimus bp. of Nicomedia was beheaded (Eus. H. E. viii. 6). Hierocles as author and magistrate silenced by torture those whom he failed to convince. Letters were sent to Maximian and Constantius in the West, urging them to adopt like measures. The former was but too willing an instrument. The latter, more humane and disposed to a policy of toleration, was compelled to join in destroying the buildings of the Christians, and was glad if he could save their lives (Lactant. de Mort. Persec. cc. 12-16).
Individual martyrdoms may be found with more or less fulness in the Acta Sincera of Ruinart, in the Annals of Baronius, in most Church Histories, notably in Fleury, viii. and ix. Here we merely note the extent, continuance, and ferocity which distinguished this persecution from all others. In Syria, Palestine, Egypt, Western Africa, Italy, and Spain the passions of men were let loose, and raged without restraint. In Gaul and Britain only was there any safety. Constantius was said (Eus. Vit. Const. i. 16) to have shewn a marked preference for those who were true to their religion, and refused to sacrifice. Elsewhere every town in the empire witnessed acts of incredible cruelty. The wish to destroy all the sacred books of the Christians, and all the accessories of their worship, led men to seize on the deacons, readers, and others connected with the churches, and to torture them till they gave them up. In Dec. 303, Diocletian went to Rome to celebrate with Maximian the 20th anniversary of his accession. At the Vicennalia the licence of the people offended him, and he left after two weeks for Ravenna. There he was attacked by a severe illness, which detained him for some months. Slowly he made his way to Nicomedia, where he became worse. Prayers were offered for his recovery in all the temples. It was rumoured that his death was concealed till the arrival of Galerius. When he appeared to contradict the rumour, he was so altered that he could hardly be recognized. His mind, it was said, was seriously affected. Galerius came, but it was to press on the emperor the duty and expediency of resigning. Maximian had been already persuaded to do so. After a feeble resistance Diocletian yielded. The two Caesars were to become Augusti. He would fain have named Maxentius the son of Maximian and Constantine the son of Constantius to take their place; but Galerius coerced or persuaded him to appoint Maximin and Severus, in whom he hoped to find more submissive instruments. When the formal acts had been completed, the emperor laid aside his official names Diocletianus and Jovius, and returned to the simple Diocles of his youth. For the history of the following year see Galerius and Constantine. The retired emperor settled at Salona, on the coast of Dalmatia, and occupied himself with building and gardening, and refused to abandon his cabbages for the cares of the state. In 310 Maximian, after vainly struggling against the growing power of Constantine, who had succeeded Constantius, was compelled to end his life by his own hands. In 311 Galerius died in the agonies of a loathsome and horrible disease, and before his death confessed, by an edict of toleration, that the attempt which he had made to crush Christianity had failed. Diocletian survived to witness the alliance between Constantine and Licinius, to receive and decline an invitation to a conference with them at Milan, to hear that Constantine had charged him with conspiring first with Maxentius and then with Maximian, and had ordered his statue and that of Maximian to be thrown down in every part of the empire. In a.d. 313 the end came, some said through poison (Aurel. Vict. Epist. 39), to avoid a worse fate at the hands of Constantine and Licinius. It was characteristic of his fate as representing the close of pagan imperialism, that he was the last emperor who celebrated a triumph at Rome, and the last to receive the honour of apotheosis from the Roman senate (Preuss, p. 169).