At the time when Robert Jolivet was building the new ramparts, from about 1415 to 1420, the town had greatly increased towards the south, and even setting aside the dangerous proximity of the English at Tombelaine, some more extensive system of defence than that afforded by the fortifications of the fourteenth century was imperatively needed to secure the place against attack. Robert Jolivet incorporated his new walls on the east with those of the preceding century, which, following the escarpments of the cliff, descend to the beach, and are protected by the northern tower. These walls he flanked with an additional tower projecting considerably from the surface, which was destined to command the adjoining curtains and protect the main line of his defences. He then carried his walls round to the south of the rock and strengthened them by five other towers. The last of these, known as the _Tour du Roi_, forms the south-eastern projection of the place, and commands the western gate of the town. The walls and their sloping bases are defended by stone machicolations above, the consoles of which support open crenellated parapets. Several of the towers were roofed, and afforded shelter for the defenders of the ramparts. After leaving the _Tour du Roi_ the walls turn off at a right angle and unite themselves to the abrupt declivities of the rock by means of a series of steps and covered ways, commanded by a fortified guard-room. Even the inaccessible peaks of the rock itself are fortified and connected with the defences of the abbey on the south. At the beginning of the fifteenth century, and still more notably towards its close, firearms had been successfully used in various sieges, and had made such rapid progress that the whole system of attack and defence was transformed. Towers gave way to bastions, the terraces of which became batteries, while the battlements of the earlier mode were replaced by epaulments. Machicolations which were now merely a traditional decoration at last disappeared altogether, and military science gradually took the place of architecture, for which there was henceforth little scope in this particular field. CHAPTER II CASTLES AND KEEPS, OR DONJONS