I must lastly deal as briefly as possible with the subject of knight service. The view of modern historians has been that this was gradually evolved during the Norman period out of a pre-conquestual obligation to provide one armed man for every five hides held. As against this I have advanced the theory[121] that the whole arrangement was introduced _de novo_ at the Conquest, when the Conqueror assessed the fiefs he granted in terms of _the five-knight unit irrespective of hidation_. Put in a less technical form my theory is that the Conqueror called on the holder of every considerable fief to furnish a contingent of five knights, or some multiple of five, to the feudal host.[122] And this he did arbitrarily, without reckoning the ‘hides’ that might be contained in the fief. Further, by the _argumentum ad absurdum_, I showed that if every five hides had to provide a knight, there would be nothing, or less than nothing, left for the tenant-in-chief.[123] It was of this new theory that Professors Pollock and Maitland observe, in their history of English Law (i. 238–9), that they regard it “as having been proved by Mr. Round’s convincing papers.” Mr. Oman, however, leans to the now exploded theory, and holds that under Norman rule “the old notion that the five hides must provide a fully armed man was remembered;”[124] and that though “some lay tenants-in-chief” got off easily, “the majority were obliged to supply their proper contingent.”[125] He then proceeds: It has been clearly shown of late, by an eminent inquirer into early English antiquities, that the hidage of the townships was very roughly assessed, and that the compilers of Domesday Book incline towards round numbers. Now apart from the fact that this “eminent inquirer,” my friend Professor Maitland to wit, gives me full credit for having been first in the field[126]--a fact which Mr. Oman, with my book before him, of course carefully ignores--his words show that he cannot understand the simplest historical theory. Professor Maitland and I have dwelt on the antiquity of this assessment, with which “the compilers of Domesday Book” had no more to do than Mr. Oman himself, and which indeed the compilation of that book has almost utterly obscured. From the fact of the five-hide unit Mr. Oman argues “that there was little difficulty in apportioning the military service due from the tenants-in-chief who owned them,”[127] though such apportionment, as I have shown, would result in an actual absurdity.[128] Indeed, Mr. Oman himself observes that the tenant-in-chief, to discharge his obligation, “might distribute the bulk of his estate in lots roughly averaging five hides to subtenants, who would discharge the service for him,”[129] although a moment’s consideration will show that this process would absorb not “the bulk,” but the whole of his estate.