Any archæologist comparing the plans will see at once that my statement is correct, and that the plan (compare the section) shows absolutely nothing beyond the actual ditch of the mound. I offered to submit the question to Mr. St. John Hope’s decision,[114] but Mr. Oman would submit it to no one but his friend and coadjutor, Mr. York Powell, who is not known as an authority on these works, and who is hostile to myself because I exposed Mr. Freeman![115] Having now shown that, in his own words, Mr. Oman “cannot read the simplest military sketch,” I pass to the siege of Rochester Castle, famous for its rectangular keep, in 1264. This was an event that deserves attention in a ‘History of the Art of War,’ for John had breached the keep by mining half a century before, and the stately structure had now to stand an energetic siege at the hands of Simon de Montfort. A striking passage in Rishanger’s Chronicle tells us that, advancing from London, comes autem de Leycestria, vir in omnibus circumspectus, machinas et alia ad expugnationem castri necessaria secum a civitate Londoniarum per aquam et per terram transvehi præcepit, quibus inclusos vehementer impugnavit, nec eos indulgere quieti permisit; exemplum relinquens Anglicis qualiter circa castrorum assultationes agendum sit qui penitus hujusmodi diebus illis fuerant ignari.[116] The barons promptly stormed the ‘outer bailey’ of the castle (April 19),[117] and strove desperately to gain the keep, till, a week later, they fled suddenly at the news of the king’s advance on London.[118] But so vigorous were the siege operations by attack, battery, and mining, that they were on the point of succeeding when they had to raise the siege.[119] Surely a ‘History of the Art of War’ should mention the above remarkable allusion to Simon’s mastery of siege operations, and to his teaching the English, who were then ignorant of the subject. But all that Mr. Oman tells us is that-- the massive strength of Gundulf’s Norman keep was too much for such siege appliances as the earl could employ. The garrison under John de Warenne, the Earl of Surrey, held their own without difficulty (p. 416). We have seen that, on the contrary, the keep was on the point of being taken. But what are we to say to the words, “_Gundulf’s_ Norman keep”? “It was long the custom,” as Mr. Clark wrote, “to attribute this keep to Gundulf, making it contemporaneous, or nearly so, with the Tower of London”; but, more than thirty years ago, it was shown by Mr. Hartshorne (in the ‘Archæological Journal’) that it was built in later days under William of Corbeuil (1126–1136).[120] No one, in the present state of our knowledge, could suppose that Gundulf was its builder; and it is obvious that a writer who does must have yet everything to learn on Norman military architecture. * * * * *