The study of earthworks has been one of the most neglected subjects in English archæology until quite recent years. It may even be said that during the first half of the 19th century, less attention was paid to earthworks than by our older topographical writers. Leland, in the reign of Henry VIII., never failed to notice the "Dikes and Hilles, which were Campes of Men of Warre," nor the "Hilles of Yerth cast up like the Dungeon of sum olde Castelle," which he saw in his pilgrimages through England. And many of our 17th- and 18th-century topographers have left us invaluable notices of earthworks which were extant in their time. But if we turn over the archæological journals of some fifty years ago, we shall be struck by the paucity of papers on earthworks, and especially by the complete ignoring, in most cases, of those connected with castles. The misfortune attending this neglect, was that it left the ground open to individual fancy, and each observer formed his own theory of the earthworks which he happened to have seen, and as often as not, stated that theory as a fact. We need not be surprised to find Camden doing this, as he wrote before the dawn of scientific observation; but that such methods should have been carried on until late in the 19th century is little to the credit of English archæology. Mr Clark's work on _Mediæval Military Architecture_ (published in 1884), which has the merit of being one of the first to pay due attention to castle earthworks, counterbalances that merit by enunciating as a fact a mere guess of his own, which, as we shall afterwards show, was absolutely devoid of solid foundation. The scientific study of English earthworks may be said to have been begun by General Pitt-Rivers in the last quarter of the 19th century; but we must not forget that he described himself as a pupil of Canon Greenwell, whose careful investigations of British barrows form such an important chapter of prehistoric archæology. General Pitt-Rivers applied the lessons he had thus learned to the excavation of camps and dykes, and his labours opened a new era in that branch of research. By accumulating an immense body of observations, and by recording those observations with a minuteness intended to forestall future questions, he built up a storehouse of facts which will furnish materials to all future workers in prehistoric antiquities. He was too cautious ever to dogmatise, and if he arrived at conclusions, he was careful to state them merely as suggestions. But his work destroyed many favourite antiquarian delusions, even some which had been cherished by very learned writers, such as Dr Guest's theory of the "Belgic ditches" of Wiltshire.