The period covered in this volume begins a year and a half after the death of Iulius Caesar and closes at the end of A.D. 69, more than a year after the death of Nero, the last of the Julio-Claudian emperors. His successors, Galba, Otho and Vitellius had ruled briefly and disappeared from the scene, leaving Vespasian as the sole claimant to the throne of empire. This was a period which witnessed the most profound transformation in the political configuration of the res publica. In the decade after Caesar's death constitutional power was held by Caesar's heir Octavian, Antony and Lepidus as tresviri rei publicae constituendae. Our narrative takes as its starting-point 27 November 43 B.C., the day on which the Lex Titia legalized the triumviral arrangement, a few days before the death of Cicero, which was taken as a terminal point by the editors of the new edition of Volume IX. By 27 B.C, five years after the expiry of the triumviral powers, Octavian had emerged as princeps and Augustus, and in the course of the next forty years he gradually fashioned what was, in all essentials, a monarchical and dynastic rule which, although passed from one dynasty to another, was to undergo no radical change until the end of the third century of our era.