I have tried to write with impartiality—a virtue which one admires the more after a close reading of original authorities who, practically without exception, were bitter and malevolent partisans. The truth, therefore, is not always easily recognised, nor has recognition been made the easier by the polemical writers of succeeding centuries who have dealt with that side of Constantine’s career which belongs more particularly to ecclesiastical history. In narrating the course of the Arian Controversy and the proceedings of the Council of Nicæa I have been content to record facts—as I have seen them—and to explain the causes of quarrel rather than act as judge between the disputants. And though in this branch of my subject I have consulted all the original authorities who describe the growth of the controversy, I have not deemed it necessary to read, still less to add to, the endless strife of words to which the discussion of the theological and metaphysical issues involved has given rise. On this point I am greatly indebted to, and have made liberal use of, the admirable chapters in the late Canon Bright’s _The Age of the Fathers_. Other authorities, which have been most useful to me, are Boissier’s _La Fin du Paganisme_, Allard’s _La Persécution de Dioclétien et le Triomphe de l’Eglise_, Duruy’s _Histoire Romaine_, and Grosvenor’s _Constantinople_. J. B. FIRTH. LONDON, October, 1904. [Illustration] CONTENTS CHAPTER I. PAGE THE EMPIRE UNDER DIOCLETIAN 1 CHAPTER II. THE PERSECUTION OF THE CHURCH 12 CHAPTER III. THE ABDICATION OF DIOCLETIAN AND THE SUCCESSION OF 39 CONSTANTINE CHAPTER IV. CONSTANTINE AND HIS COLLEAGUES 56 CHAPTER V. THE INVASION OF ITALY 73 CHAPTER VI. THE VISION OF THE CROSS AND THE EDICT OF MILAN 92 CHAPTER VII. THE DOWNFALL OF LICINIUS 115 CHAPTER VIII. LAST DAYS OF PERSECUTION 134 CHAPTER IX. CONSTANTINE AND THE DONATISTS 159 CHAPTER X. THE ARIAN CONTROVERSY 189 CHAPTER XI. THE COUNCIL OF NICÆA 211 CHAPTER XII. THE MURDERS OF CRISPUS AND FAUSTA 237