The present work was conceived as a companion volume to Constantine and
Eusebius, to argue in detail dates and facts which are there assumed and made
the basis for historical interpretation and synthesis. It has inevitably also become an independent work of reference, for it sets out to establish the basic
factual framework for a period in the history of the Roman Empire which is
both obviously significant and notoriously obscure. Nevertheless, its scope
continues to reflect its genesis. I have not attempted to solve all the problems
posed by the imperial coinage or the legal sources, nor to draw up lists either of
court and financial officials or of military commanders. The emphasis lies on
emperors and imperial chronology (Part One), on the holders of the highest
administrative posts and provincial governors (Part Two), and on the administration of the empire (Part Three)—and even within these restricted fields I
have usually refrained from drawing general conclusions from the individual
facts documented.
The work has been revised and largely rewritten several times, and I am
most grateful to friends who have read one or more of the drafts, either in
whole or in part, and proposed many improvements—Drs. A. K. Bowman,
P. Brennan, and J. R. Rea, and Professors G. W. Bowersock, E. J. Champlin,
H. A. Drake, J. F. Gilliam, C. Habicht, C. P. Jones, P. Kussmaul, F. G. Β.
Millar, and Sir Ronald Syme. Their comments, particularly those of Glen Bowersock, Christian Habicht, and Fergus Millar, have made the final version far
more accurate than it would otherwise have been. Nonetheless, I am sure that
many mistakes and omissions must remain, and I hope that readers who notice
any errors or oversights will either inform me privately or publish the necessary
corrections as rapidly as possible.
I must also express my gratitude to Donna Burns, Margaret von Sant, and
Maria Pezzot for typing and retyping a difficult and complicated manuscript.