Fougères
There were cases, however, especially in walls of towns, where the curtain-tower, although projecting outside and above the wall, and covered with a timber roof, was left open at the gorge or neck, where it was flush with the curtain, so that it was simply an open tower, with a platform on the first floor, level with the rampart-walk, and a rampart-walk of its own at the level of its battlements. Such a tower could be actively employed in time of war, and had all the advantages of the ordinary closed tower in flanking the wall and cutting the rampart-walk up into sections. The numerous towers of the walls of Avignon, between the gatehouses, were arranged thus.[268] At Conway, the semi-cylindrical towers of the town walls, of which there are twenty, and the similar towers which flank the gatehouses, are open to the town: one tower only, on the south-west side of the town, where the wall turns to join the castle, is walled at the gorge. The walls of Chepstow provide further examples of open towers. At Carnarvon ([251]), the round towers on the face of the town walls are open, but the angle-towers were closed; and that at the north-west angle was entered through the town chapel, which was built against the curtain at this point. The open tower was not, as a rule, used in castles: even the small towers which flank the outer curtain at Beaumaris have a wall continued across the gorge.
Carnarvon; Tower of town wall
Every large castle was provided with a postern or sally-port. This was generally a small doorway, preferably in the base of a tower, but often in the curtain, opening on the least frequented side of the castle. In time of siege, in a castle of the ordinary plan, a postern might easily be a source of danger; and its employment in the scheme of defence was incompletely understood at first. But it was useful for the conveyance of provisions to the castle; and a postern, as at Warkworth, is often found in connection with a kitchen or store-room. Where a castle stood near a river, a water-gate, communicating with a private wharf was made. At Pembroke, where the castle stands between two water-ways, there were two water-gates, one in the south side of the outer ward, the other, as already mentioned, formed by walling in the mouth of the cave below the great hall. For the scientific employment of the postern, however, we have to look to the great castles of the later part of the thirteenth century, in which the means of defence described in this chapter were perfectly co-ordinated; and, with the introduction of a new plan, the last signs of a merely passive strength vanished from the castle.
CHAPTER X
THE EDWARDIAN CASTLE AND THE CONCENTRIC PLAN
Castles like Carew, enclosing a rectangular area with round towers at the angles, were the fruit of the transition in the course of which the fortified curtain wall took the place of the passive strength of the keep. At Carew the castle was protected upon its most exposed side by outer defences of stone; but on all other sides it presented a single line of defence, flanked by the four formidable angle-towers. A castle thus defended was, like the early stone castles at Richmond and elsewhere, a keep in itself; but its wall no longer depended merely upon its passive strength, but was calculated to resist attacks on which the builders of Richmond and Ludlow had no means of reckoning.