CA'SSIUS, AVI'DIUS, was, according to Dion Cassius, a native of Cyrrhns in Syria, and the son of a rhetorician, Heliodorus, who was prrefect of Egypt in the joint reign of Antoninus Pius and Marcus Aurelius. Cassius served in the I'arthian wars (A.D. 162 or 165) under Lnclua Verus, in which he defeated Vologesus, and took Selenceia and Ctesiphon on the Tigris. He also served on the Danube, probably about 166. He was subsequently appointed governor of Syria, and in 170 he went to Egypt to suppress an insurrection in the lower country which was excited by some fanatics. He succeeded in putting an end to the rebellion; but a few years after (in 175) he himself rebelled against the Emperor Marcos Aurelius, and proclaimed him self Irnperator in the East. Cassius was assassinated in a few months, and his head was carried to Aurelius. The humane emperor lamented his death, and declared that he wished Cassius alive that he might upbraid him for his ingratitude. The family and children of Cassius were spared, but it is said that Commodus the son of Aurelius burnt alive all the then surviving members of the family of Cassius, on the pretence of a fresh conspiracy.
Dion Cassius, who loved a tale of scandal, says that Faustina the wife of Aurelius, being apprehensive that her husband would not live long, and considering the youth of her son Commodus, attempted to secure the interests of herself and her family by corresponding with Avidius Cassius, and urging him to proclaim himself emperor when ever he beard of the death of Aurelius, and take her for his wife. It is said that there was a report of the death of Aurelius, and that this was the immediate occasion of Cassius proclaiming himself emperor.
It is also said that he was himself the author of the report of the death of Aurelius. The letters between Aurelius and his wife Faustina on the occasion of the rebellion of Cassius are probably not genuine. Vulcatius attempts to show from these letters that Faustina was not privy to the design of Cassius.
(Vulcatius Gallicanue, Avidius Cassius ; Dion Cassius, lib. 1'71 ; Tillemont, I1i.sfDire dee Empereurs, Vol. ii.)