Dio Cassius 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 AD 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 circumstantial in relating what passed under his own eyes. We have fragments remaining of the first thirty-six books: but there is a considerable portion of the thirty-fifth book, on the war of Lucullus against Mithridates, and of the thirty-sixth, on the war with the pirates and the expedition of Pompey against the king of Pontus. The books that follow, to the fifty-fourth inclusive, are nearly all complete: they cover the period from BC 65 to BC 12, or from the eastern campaign of Pompey and the death of Mithridates to the death of Marcus Vipsanius Agrippa. The fifty-fifth book has a considerable gap in it. The fifty-sixth to the sixtieth, both included, which comprehend the period from AD 9 to AD 54, are complete, and contain the events from the defeat of Varus in Germany to the death of Claudius. Of the following twenty books we have only fragments and the meagre abridgment of John Xiphilinus, a monk of the eleventh century. The eightieth or last book comprehends the period from AD 222 to AD 229, in the reign of Alexander Severus. The abridgment of Xiphilinus, as now extant, commences with the thirty-fifth and continues to the end of the eightieth book. It is a very indifferent performance, and was made by order of the emperor Michael VII Parapinaces.
The fragments of the first thirty-six books, as now collected, are of four kinds:
This entry was based on H.T. Peck's Harpers Dictionary of Classical Antiquities (1898)