South of the ridge, and close behind and covered by the castle, is the town of Corfe, from which the castle hill rises steeply, to descend almost vertically upon its east, west, and north sides. The northern, or highest point, is occupied by the keep and principal buildings of the castle.
The stream called the Wicken, and its tributary, the Byle brook, each turning a mill, flow from the south-west and south-east round either side of the town, and, girdling the base of the castle hill, unite just below St. Edward’s bridge to form the Corfe river, which flows into Poole harbour. Between the town and the castle, where the two streams approach within a furlong of each other, a deep and bold though dry trench has been cut across the root of the peninsula, and thus forms the great outer ditch which divides the castle from the town.
The castle, in its present form, may be called concentric, but it has been constructed, if not designed, at three principal periods, having been originally a Saxon palace, then a Norman, and afterwards an Edwardian fortress.
It is composed of a keep standing in an inner ward, of a middle, and of an outer ward. The survey by Ralph Treswell, in 1586, subdivides the inner ward into two, and shows a wall across the outer ward, which has disappeared, and was probably modern.
In plan it is an irregular triangle, the walls following the crest of the hill. The great gateway caps the southern or lowest angle; the Buttavant Tower, the western; and the inner ward forms the obtuse, highest, or eastern angle. The south-west, the longest front, is concave. It extends 270 yards from the gatehouse to the Buttavant, and its lower two-thirds is the part of the enceinte most jealously defended, and upon the overthrow of which the destroyers have expended their greatest energies. The north, or upper front, too high for attack, measures about 200 yards, and the eastern front about the same.
The area within the walls is about 3¼ acres; but, from the excessive steepness of the ground, much of the outer and part of the middle ward could never have been turned to account. The lower part of the outer, the western portion of the middle, and the eastern part of the inner ward, are the only flat spaces.
The outer, by much the largest ward, is contained within the great gatehouse, the east curtain strengthened by the Horseshoe and Plukenet Towers, and the west curtain, upon which are four mural towers. The steep, upper part of the ward rises to the wall of the inner, and the wall and gatehouse of the middle ward. It is traversed by a fosse, attributed to King John, which extends from the Plukenet Tower to the front of the middle gatehouse, and is thence continued outside the works down the hill-side.
A permanent stone bridge, about 100 feet long by 20 feet broad, crosses the moat, and leads up to the great gateway. It is of four arches, springing from three solid piers, and the roadway, which has now no parapets, is about 30 feet above the bottom of the moat. The masonry ceases about 18 feet from the portal, and the interval, now filled with earth, was probably spanned by a drawbridge. The arches are about one-third of a circle, and the voussoirs in two rings, without bond, 8 inches thick, and from 1 foot to 3 feet in length. The piers may be of Perpendicular date, but the arches are probably due to Sir Christopher Hatton.
The outer gatehouse is composed of two drums, flanking the portal, and produced rearward into a rectangular building, now partially destroyed. The drums, about 20 feet diameter, are solid to the base of the upper story, now removed, but of which the lower ends of the loops remain.
The portal, 13 feet wide, enters a vaulted passage, now 26 feet, and which may have been 36 feet long. First is the portal, now without jambs, and beneath a segmental arch, 4 feet 11 inches broad. Then (as shown in the accompanying section, Fig. I.) a chase, or single machicolation, 6 inches broad. Then a second arch, 3 feet 9 inches broad. Then a chase, 5 inches broad, and a circular groove of 9 inches diameter and 7 inches opening, at which the passage narrows by 20 inches, being an opening of 11 feet 4 inches. Then follows an arch of 1 foot 6 inches breadth, and a chase of 16 inches.