The following essay is an attempt to deal with an interesting branch of Roman military history which has not previously been made the subject of an independent treatise. In a study of this kind, which relies largely upon epigraphical evidence to which additions are constantly being made, it is equally necessary that the scattered material available should at intervals be collected and utilized, and that the unfortunate collector should realize that his conclusions will inevitably be revised in the future in the light of fresh evidence. I hope, accordingly, that I have made some use of all sources of information available without acquiring or expressing excessive confidence in the finality of my deductions. Students of the military system of the Roman Empire may complain that a certain number of complicated questions are too summarily disposed of in the following pages, but if discussion of the evidence in detail has been occasionally omitted with the idea of keeping the size of this book within reasonable limits, I hope that I have been careful to indicate where uncertainty lies.

I have in many places been glad to acknowledge my indebtedness to my predecessors in this field of study, who in one branch of the subject or another have removed so many difficulties from my path. To two scholars, however, my debt is too extensive and general to have received adequate recognition in the footnotes. Mommsen’s article, ‘Die Conscriptionsordnung der rÖmischen Kaiserzeit,’ was written thirty years ago; I have, I hope, been diligent in collecting the evidence which has since accumulated, but I have found little to induce me to leave the path indicated by the founder of the scientific study of the Roman Empire. I owe much to Professor A. von Domaszewski’s ingenious and comprehensive work, Die Rangordnung des rÖmischen Heeres, and feel my obligation to its learning and suggestiveness none the less that I have sometimes been compelled to differ from the conclusions stated in it. I am also deeply indebted to Professor Haverfield for constant encouragement and much valuable criticism, and can only wish that this essay were a more adequate testimony to the value of his influence upon the study of Roman history at Oxford. I desire also to express my gratitude to my colleague, Mr. N. Whatley, of Hertford College, for reading this essay in manuscript, and making many valuable suggestions.

G. L. CHEESMAN.

New College, Oxford.