CASTLE, a word derived from the Latin castellum, a diminutive of castrum, a fortress or stronghold. The word castellum was fre quently applied by the Romans as a military term to denote a redoubt. The word has come to be used as the designation of those strong holds which, in feudal times, served at once as residences and as places of defense for the nobles, and which continued to exist until the invention of gunpowder changed the whole system of fortification. The royal residences among the Franks resembled in some points both the Roman villa and the Roman camp, and those of the Frankish nobles differed little from those of the kings except in point of simplicity. Strictly speaking, only the grand feudatories had the right to erect fortified castles, and then only after receiving the royal consent; but the grand feudatories very early began to take it upon themselves to grant the privilege of erect ing castles to their vassals, and these again to those of a still lower grade. In this way large numbers of castles began to spring up at an early period in France, Germany, England and elsewhere.
The castles of the Norman Conquest in Eng land were probably the first stone buildings erected there. The great square keep of Roch ester Castle is probably of this period; it is about 70 feet square, with projecting corner turrets, and as it now stands is 100 feet high, but the battlements have been altered and its original character lost. A heavy wall divides the huge structure into two nearly equal parts, and within this wall a well is arranged which communicates with all three stories; the outer walls are 12 feet thick at the base and the masonry is very perfect. Little is known of the ancient disposition of the minor buildings. There is no doubt that a high and battlemented wall enclosed a court or perhaps two courts, an inner and an outer bail, as they are called; that the keep was enclosed by the inner wall, but al ways so near the wall that a postern could com municate with the outer moat, and that within the enclosing wall, often built up against its in terior face, were stables and storerooms, and also lodgings for the garrison, which last, how ever, might be temporary structures. This wall was always surrounded by a deep and broad moat, which might be filled with water in a low country, or, when dry, served merely to in crease the effective height of the walls and to disarrange the approach of the besiegers. There wa.s always a chapel, but in Rochester Castle this is built against the southeast corner of the keep and opens from its principal floor. In such an early castle the keep is the only very strong place, as a vigorous attack would breach or• scale the otter wall very soon.
The castles of the 12th and 13th centuries were far more elaborate, and their tendency was toward separate posts, each defensible by itself. Every tower could be shut up and de fended, its little garrison resisting even alter the neighboring works had been captured or rendered indefensible. This arrangement had
the disadvantage that a very bold and sudden attack might capture the strongest parts of the castle, even the keep itself, before assistance could come to it. The typical castle of the 12th century is the famed Chateau Gaillard in Nor mandy, and of the 13th century the famous castle at Coney, near Laon in northern France; and in the British Isles, Kidwelly in Wales, which remains in a perfectly traceable condi tion.
The perfect castle was not developed until the time when gunpowder was about to make it useless. Thus the Chateau of Pierrefonds, north of Paris, and near Compiegne, was built about 1400, and in this the faults of the earlier castles were avoided. The walls are every where of nearly equal height, the galleries of defense are continuous so that the soldiers of the garrison may run easily the whole length of the walls, and these galleries are two or even three deep, allowing the defenders to throw a prodigious rain of projectiles upon any attacking party. These galleries, built of stone, replace the temporary wooden galleries, always put up on the walls of earlier castles when an attack was anticipated. It is to be noted that the attack and defense in mediaeval fortifica tions was vertical; the higher the wall the more formidable was the blow delivered by a falling ball of stone, or a timber or iron bar; while the projectiles from crossbows and mili tary engines would certainly lose nothing, and .
the garrison this way was removed far above the assailant, who must come close under the walls to attack. This attack, then, consisted, in the case of a well-defended place, chiefly in breaching or undermining the walls. Escalade was only possible where the garrison was weak or in poor condition or surprised.
Castles often had outer works, thus the barbican or barbacan is strictly a defense built outside of the principal gate and intended to keep the enemy away from it for a certain length of time. When a castle was near a river an outwork would be built on the other bank, covering the bridge leading to the castle. When the site was high, with steep approaches, a covered way might be built to protect the whole of the path leading up to the castle, and the foot of this would have an outwork or strong post capable of some defense.
The introduction of fire-arms and especially of cannon heavy enough to breach the walls compelled a change in the old castles, which were often ruined as consistent pieces of me dixval fortification by having their towers cut down to accommodate artillery of defense. A round stone tower 200 feet high would be cut down to a kind of bastion 30 feet high, with a parapet and embrasures for cannon around its platform. Even this was only temporary, for It was soon found that the effect of artillery fire was irresistible by stone walls, and these were abandoned for the sloping rampart of earth introduced in the 16th century. See