Flavius Josephus, The Wars of the Jews
William Whiston, A.M., Ed.

[219] AND now, in the fourth year of the reign of Vespasian, it came to pass that Antiochus, the king of Commagene, with all his family, fell into very great calamities. The occasion was this: Cesennius Petus, who was president of Syria at this time, whether it were done out of regard to truth, or whether out of hatred to Antiochus, (for which was the real motive was never thoroughly discovered,) sent an epistle to Caesar, and therein told him that Antiochus, with his son Epiphanes, had resolved to rebel against the Romans, and had made a league with the king of Parthia to that purpose; that it was therefore fit to prevent them, lest they prevent us, and begin such a war as may cause a general disturbance in the Roman empire. Now Caesar was disposed to take some care about the matter, since this discovery was made; for the neighborhood of the kingdoms made this affair worthy of greater regard; for Samoseta, the capital of Commagene, lies upon Euphrates, and upon any such design could afford an easy passage over it to the Parthians, and could also afford them a secure reception. Petus was accordingly believed, and had authority given him of doing what he should think proper in the case; so he set about it without delay, and fell upon Commagene before Antiochus and his people had the least expectation of his coming: he had with him the tenth legion, as also some cohorts and troops of horsemen. These kings also came to his assistance: Aristobulus, king of the country called Chalcidene, and Sohemus, who was called king of Emesa. Nor was there any opposition made to his forces when they entered the kingdom; for no one of that country would so much as lift up his hand against them. When Antiochus heard this unexpected news, he could not think in the least of making war with the Romans, but determined to leave his whole kingdom in the state wherein it now was, and to retire privately, with his wife and children, as thinking thereby to demonstrate himself to the Romans to be innocent as to the accusation laid against him. So he went away from that city as far as a hundred and twenty furlongs, into a plain, and there pitched his tents.