Cassius Dio Cocceianus (c. 155– after 229), known in English as Cassius Dio or Dio Cassius, was a noted Roman historian and public servant. Dio published a Roman history embracing a period of 983 years, from the arrival of Aeneas in Italy through the subsequent founding of Rome and then to 229. Of the eighty books, written over twenty-two years, many survived into the modern age intact or as fragments, providing a detailed perspective on Roman history.
The son of Cassius Apronianus, a Roman senator, Cassius Dio was born at Nicaea in Bithynia. In his writings, he adopted the prevailing Greek language of his native province, but he must be considered as a Roman.
Cassius Dio passed the greater part of his life in public service. He was a senator under Commodus and governor of Smyrna after the death of Septimius Severus; and afterwards suffect consul around 205, as also proconsul in Africa and Pannonia. Alexander Severus entertained the highest esteem for him, and made him consul for the second time, with himself in 229, though the Praetorian Guards, irritated against him on account of his severity, had demanded his life. Following his second consulship, being advanced in years, he returned to his native country, where he died.
Dio published a Roman History, in eighty books, the fruit of his researches and labours of twenty-two years. It embraced a period of 983 years, extending from the arrival of Aeneas in Italy, and the subsequent founding of Rome, to 229. Down to the time of Julius Caesar, he only gives a summary of events; after this, he enters somewhat more into details; and from the time of Commodus he is very circumspect in relating what passed under his own eyes.
We have fragments remaining of the first 36 books: but there is a considerable portion of the 35th book, on the war of Lucullus against Mithridates VI of Pontus, and of the 36th, on the war with the pirates and the expedition of Pompey against the king of Pontus. The books that follow, to the 54th inclusive, are nearly all complete: they cover the period from 65 BC to 12 BC, or from the eastern campaign of Pompey and the death of Mithridates to the death of Marcus Vipsanius Agrippa. The 55th book has a considerable gap in it. The 56th to the 60th, both included, which comprehend the period from 9 to 54, are complete, and contain the events from the defeat of Varus in Germany to the death of Claudius. Of the following 20 books, we have only fragments and the meagre abridgment of John Xiphilinus, a monk of the XI century. The 80th or last book comprehends the period from 222 to 229, in the reign of Alexander Severus. The abridgment of Xiphilinus, as now extant, commences with the 35th and continues to the end of the 80th book. It is a very indifferent performance, and was made by order of the emperor Michael VII Parapinaces.
The fragments of the first 36 books, as now collected, are of four kinds:
Dio has taken Thucydides for his model, but the imitator is not comparable with his original either in arrangement and the distribution of materials or in soundness of view and accurate reasoning. His style is generally clear, where there appears to be no corruption of the text, though full of Latinisms. His diligence is unquestionable, and, from his opportunities, he was well acquainted with the circumstances of the Empire during the period for which he is a contemporary authority.