The present work is the outcome of a wish expressed to me from more than one quarter that I would reprint in a collected form, for the convenience of historical students, some more results of my researches in the history of the eleventh and twelfth centuries. But to these I have added, especially on Domesday, so much which has not yet seen the light, that the greater portion of the work is new, while the rest has been in part re-written. The object I have set before myself throughout is either to add to or correct our existing knowledge of facts. And for this I have gone in the main to records, whether in manuscript or in print. It is my hope that the papers in this volume may further illustrate the value of such evidence as supplementing and checking the chroniclers for what is still, in many respects, an obscure period of our history. To those in search of new light on our early mediaeval history, I commend the first portion of this work, as setting forth, for their careful consideration, views as evolutionary on the Domesday hide and the whole system of land assessment as on the actual introduction of the feudal system into England. Although I have here brought into conjunction my discovery that the assessment of knight-service was based on a five-knights unit, irrespective of area or value, and my theory that the original assessment of land was based on a five-hides unit, not calculated on area or value, yet the two, one need hardly add, are, of course, unconnected. The one was an Anglo-Saxon system, and, as I maintain, of early date; the other was of Norman introduction, and of independent origin. My theories were formed at different times, as the result of wholly separate investigations. That of the five-hides unit was arrived at several years ago, but was kept back in the hope that I might light on some really satisfactory explanation of the phenomena presented. The solution I now propound can only be deemed tentative. I would hope, however, that the theories I advance may stimulate others to approach the subject, and, above all, that they may indicate to local students, in the future, the lines on which they should work and the absolute need of their assistance. Perhaps the most important conclusion to which my researches point is that Domesday reveals the existence of two separate systems in England, co-extensive with two nationalities, the originalfive hides of the 'Anglo-Saxon' in the south, and the later six carucates of the 'Danish' invaders in the north.Ê