These early camps form merely the preface to our subject, and attention need be called only to some general features. Their character, like that of the medieval town or castle, was strictly defensive. They were the strongholds of races whose weapons were of a very primitive description, and could carry to no great range. What their inhabitants needed was an impregnable fortress, within which they and their herds could be well sheltered from attack. They belong to a day before siege operations were possible. To carry them, a determined onset and a hand-to-hand fight were necessary. Their strength therefore depended on the complexity of their defences. No enemy could hope to scale the flanking banks of Maiden Castle, one by one. The entrances to the camp, at its eastern and western ends (3), were so elaborately concealed by the overlapping ramparts, that even on a ground-plan they are far from obvious; and it was almost inevitable that an attacking force, without a guide acquainted with the ground, would be decoyed into a _cul-de-sac_ and overwhelmed by the missiles of the defenders on the ramparts. [Illustration: Old Sarum (From Mr Hadrian Allcroft’s _Earthwork of England_ by kind permission of Messrs Macmillan & Co.)] The steepness of the bank itself constituted a formidable means of defence. At Maiden Castle the great northern banks rise to a height of 60 feet or more. The top of the outer bank of Old Sarum (4) is 106 feet above the level of the ditch below.[2] In many cases, and probably in all, the inner bank was crowned by a stockade, consisting of a series of upright stakes, between and round which was twined an impenetrable hedge of thorns. The plateau or berm which was sometimes left behind the parapet of the bank, where there was more than a single bank and ditch, was a valuable asset to the defenders of prehistoric strongholds, forming an advance post from which they were able to wield their missiles freely; while sometimes the summit of one or more of the outer banks was made for the same purpose into a broad platform, which allowed greater freedom of movement. The parapet or counterscarp of the outer ditch was probably defended by a stockade, and it is known that in some cases sharpened stakes or stones were fixed firmly in the bottom of the ditches. [Illustration: Bury Ditches]