Roman emperor, April, A. D. 217--June, A. D. 218. M. OPELIUS (OR OPILIUS) MACRINUS, afterwards M. OPELIUS SEVERUS MACRINUS, at whose instigation Caracalla was assassinated, when marching to encounter the Parthians, was a native of Caesareia in Mauritania, and was born of very humble parents, in the year A. D. 164. Having been recommended to the notice of Plautianus, the all-powerful favourite of Septimius Severus, he was admitted into his employment, and narrowly escaped being involved in the destruction of his patron. [PLAUTIANUS.] Having subse. quently received several appointments of trust in the imperial household, he was at length named praefect of the praetorians, by Caracalla, and discharged the duties of that high office with the greatest prudence and integrity, whenever he was permitted to follow the dictates of his own inclinations uncontrolled. The death of Caracalla took place on the 8th of April, A. D. 217 [CARACALLA], and on the 11th Macrinus, who had hitherto abstained from coming forward openly, lest he might be suspected of having participated in the plot, having, through the secret agency of his friends, succeeded in gaining over the soldiers by the promise of a liberal donative, was proclaimed emperor, the title of Caesar being at the same time conferred upon his son Diadumenianus [DIADUMENIANUS]. He immediately repealed the additional tax imposed by his predecessor on manumissions and inheritances, and expressed a determination to abolish all unlawful exactions both in the city and in the provinces. The senate, filled with joy on receiving intelligence of the death of their hated tyrant, gladly confirmed the choice of the army.

The emperor at once marched to meet Artabanus the Parthian, who, burning with rage on account of the dishonour and loss sustained through the treachery of Caracalla, and confident in his own strength, had haughtily rejected all offers of accommodation, except upon such terms as it was impossible to accept. The opposing hosts encountered near Nisibis, the Romans were signally defeated, and after having been compelled to purchase the forbearance of the conqueror, by a great sum of money and heavy sacrifices, retired, covered with disgrace, into Syria. At the commencement of the following year a discontented and mutinous spirit began to be openly displayed in the legions, who found the sovereign of their choice far less indulgent and open-handed than the son of Severus. Taking advantage of these feelings, Julia Maesa [MAESA], who was at that time living at Emesa, persuaded the detachments quartered in the vicinity that her grandson Elagabalus was in reality the child of Caracalla, and having seduced them from their allegiance by lavish offers, induced them to receive the boy into their camp, and to acknowledge him as their prince. Macrinus advanced to Antioch to crush the impostor, but after an engagement, fought on the 8th of June, A. D. 218, in which great cowardice was displayed on both sides, the fortune of the day having been eventually decided by the energy and bold example of Maesa and Soemias, he was compelled to fly, and, casting away his royal robes, reached Chalcedon disguised in mean attire. There he was quickly betrayed, was dragged back, and slain in Cappadocia, in the fifty-fourth or fifty-fifth year of his age, after a reign of fourteen months. His head, and that of his son, who had been discovered and put to death elsewhere, were stuck upon poles, and carried about in triumph. If we can trust Capitolinus, he scarcely deserves our pity, for he is represented by the Augustan historian as haughty, blood-thirsty and inhumanly cruel in the infliction of punishments. Great complaints were made of the number of unfitting and unworthy persons invested by him with the highest dignities. (Dio Cass, Ixxxviii. 11-41; Capitolin. Macrin.; Aurel. Vict de. Caes. 22, Epit. 22; Eutrop. 8.12; Zonar. 12.13.)