Marcus Aurelius Antoninus, a Roman emperor, son-in-law and successor of Antoninus Pius, born A. I). 121, ascended the throne in 101, died March 17, 180. His original name was Marcus Annius Verus. After the death of Ceionius Commodus, better known as Verus, Hadrian selected Antoninus Pius to succeed him, and caused the latter in his turn to adopt Marcus Annius and Lucius Verus, the son of Commodus, as his ultimate successors. During the reign of Antoninus Pius, who had given to him his daughter Faustina in marriage, Marcus distinguished himself principally by his studies in philosophy, having assumed the mantle of the Stoics in his 12th year; while Verus so far disgraced himself by his early profligacy, that his adoptive father disinherited him, and, procuring the nomination of Marcus Aurelius as sole successor by the senate, associated him with himself in the empire. On his accession, however, Marcus Aurelius, who now assumed the name of Antoninus, gave Verus an equal share of the government. Shortly after his accession a war broke out with the Parthians in the east, the command of which, nominally given to Verus, was virtually held by his lieutenants, the principal of whom, Avidius Cassius, overran Mesopotamia, destroyed Seleucia, and penetrated as far as Babylon, while one of his colleagues made himself master of Armenia, replaced the rightful king of the Parthians, Sozi-mus, on the throne, and reduced Vologeses, his rival and the instigator of the war, to sue for a dishonorable peace.

This outbreak was followed, or rather interrupted, by yet more dangerous hostilities in the north, extending from the sources of the Danube to the lllyrian frontier, where the barbarous tribes of the Marcomanni, Alani, Jazyges, Quadi, Sarmatians, and others, all took arms at once in such force as compelled both the emperors to proceed to the frontiers. Here they were so successful, that in 109 the enemy sued for peace, and the colleagues set out on their return for home; but Verus dy-ing of apoplexy on their journey, and the war being renewed, Marcus Aurelius again turned his face northward, and for the next five years carried on the war in person in Pannonia, without ever returning to Rome; enduring the greatest hardships with the serenity of a philosopher, while he conducted his campaigns with the skill of a soldier. On one occasion a fierce battle was fought on the surface of the frozen Danube; but the most remarkable victory was one gained over the Quadi in consequence of a sudden and terrific thunder storm, by which the Romans were saved from apparently imminent defeat, and the superstitious savages were confounded and put to rout.

This victory was generally ascribed to divine interposition, the emperor and his Romans attributing it to Jupiter Tonans, and the Christians, who composed the 12th or Meletine legion, to the influence of their prayers. Eusebius goes so far as to assert that the emperor gave to that body of men the title of the "thundering legion; " but in spite of his virtues, Marcus Aurelius persecuted the Christians. His wife Faustina, learning the danger of her husband's situation, and fearing that in case of his death, and the long minority of her young son Commodus, she should sink into a private station, entered into an intrigue with Avidius Cassius, the emperor's deputy and general in Syria, promising him her hand in case of the death of Aurelius, and encouraging him in that event to seize the reins of the government. A false report of the defeat and death of Aurelius following, Avidius Cassius assumed the purple. Despairing of pardon when he learned the falsity of the report, he persisted in his rebellion, and rapidly made himself master of several Roman provinces in Asia. While the emperor was making preparations to reduce him, the usurper was assassinated by a centurion of his own army. The conduct of Marcus Aurelius was magnanimous in the extreme.

He put no one to death in consequence of the overt treason, punished but few, and burned the letters of Cassius, in order to avoid learning who had seconded or in-stigated him in his proceedings. Faustina, who had remained in her husband's company during these compromising events, and whose privity he either did not suspect, or, more probably, did not choose to perceive, died in Cilicia, it was supposed by suicide. In 176 the emperor visited Rome after an absence of eight years, and celebrated his victories by a splendid triumph, and by a largess to every Roman citizen of eight pieces of gold; then having associated with himself in the sovereignty his unworthy son Commodus, and celebrated the young man's nuptials with Crispina, he marched in company with his expectant successor to conclude the war with the northern barbarians, and, in the midst of a career of uninterrupted triumph, died at Vindobona, now Vienna. Commodus was suspected of hastening his end. Marcus Aurelius was an excellent man and an admirable monarch. His whole life was a practical example of his own philosophic doctrines.

The only blot on his character was a cruel persecution of the Christians in Gaul; and this is so inconsistent with the spirit of his own character, with his general principles of mildness and toleration, and with the example of his predecessor, by which he was for the most part strongly influenced, that it is difficult to explain. His "Meditations," which are still extant, would be an honor to any writer of any age, and breathe the very spirit of the religion which he persecuted. The best edition is Gataker's (4to, Cambridge, 1652). The best English translation is that of George Long, "Thoughts of the Emperor Marcus Aurelius Antoninus."