A large fortified self-contained community building, usually built of stone, popular in medieval Europe.

The outer wall is called the Motte and the central tower is called the Bailey.

Various defensive capabilties were designed into the structure including drawbridges, portcullises, slotted windows for archery, and holes for pouring boiling oil.

Once the population is inside they're difficult to attack. Most successful attacks therefore relied on the element of surprise.

To castle in chess:

  • the squares between the king and the rook (castle) must be empty.
  • neither the king nor the rook must have moved.
  • the king must not be in check, move through check, or castle into check.*
  • whether or not the rook is being attacked at the time of castling does not matter.
  • the king moves exactly two squares towards the rook and the rook moves to the opposite side of the king.
  • in kingside castling, the king moves to g1 (white) or g8 (black) and the rook moves from h1 to f1 (white) or h8 to f8 (black).
  • in queenside castling, the king moves to c1 (white) or c8 (black) and the rook moves from a1 to d1 (white) or a8 to d8 (black).

The objective of castling in chess is to bring the king behind a wall of protective pawns and to bring the rook into play at the same time.

*: to clarify this rule, this means that, for instance, if the White King is going to castle kingside, moving from e1 to g1, there must be no Black pieces that threaten any of the squares e1, f1 or g1. Similarly, if the White King were to castle queenside, there must be no Black pieces that threaten the squares e1, d1 or c1.

One of my favorite stories about chess involves castling.

The story goes that a player in a tournament once castled in a thoroughly original manner: having earlier promoted a pawn on his King file to a rook, and not having moved it since it then, he castled by moving his King to K3, and the rook to K2! His opponent called him on it, and the tournament director got involved. The unorthodox player insisted that he look up the definition of castling, and, upon doing so, the TD found that the move that had been made met all the requirements listed, so he allowed it.

Because it is probably an urban legend, it is ornamented with an additional feature that makes you think only in the movies. The castling player was said to be in dire straits, but the castling move won the game by checkmating his opponent!

The move itself would have drawn gasps from the crowd if chess tournaments drew crowds, and as the realization of checkmate swept through them, the spectators would have roared. Since this never happens, we may as well continue the fantasy and envision them choosing up sides based on their opinions of the move's legality, and probably ending up lynching the tournament director.

Castle History and Concepts

When most of us think of castles, we think of the big, gray stone fortresses that dot the landscape of Europe- the residences of knights and kings, and excellent back drops for adventure films. Castles in medieval Europe developed in the uncertain period that followed the fall of the Roman Empire and its associated political and military institutions. In this volatile environment, rulers in the newborn feudal system needed a way to pacify the country- extending their presence and power, and providing themselves and their feudal servants with secure defensive points.

The earliest constructions that are recognized as castles are thought to have been built in France during the Dark Ages of Europe. The earliest form of the castle was the motte and bailey; a wood and plaster wall, with wooden crenellated paling atop it, surrounded by a defensive ditch. Within the wall was a keep, a wooden, or later stone, tower built atop an earthen mound.

Development of castle defenses was fast and brutal, however. Early wooden defenses and constructions were susceptible to attack by fire, and were replaced by more durable stone constructions. The structural and tactical weakness presented by rectilinear corners (which could be easily collapsed by being undermined with tunnels) lead to the development of rounded walls and projecting towers. Walls became thicker and higher as techniques for breaching them became more sophisticated, and were designed to allow the maximum amount of firepower (from bowmen and crossbows) to be directed at any vulnerable point.

While castle architecture in Europe was dominated by defensive concerns, castles served a variety of roles throughout the Middle Ages. On the most basic level, they provided homes for the nobles (dukes, barons, knights, and even kings) charged with administering the lands that surrounded them, as well as for the soldiers and other laborers who staffed the fortress. As the nobility often were responsible for dispensing justice and filling other administrative roles in their realms, castles often served as the center for civil and political life in their areas.

Furthermore, castles were meant to establish the visible presence of the king and his government in the countryside. In addition to their defensive mission, castles were meant to dominate the landscape and remind the peasants that their royal masters held all the cards in the land. The castle's beauty was to stem from its strength and power. Prisoners were held in its dungeons (a word derived from the French donjon, a castle keep), awaiting their ransom, judgement, or execution. A popular form of dungeon was the oubliette, a beehive shaped chamber with an opening only at the top, its name derived from the French word for 'to forget'. As in, 'his lordship will now forget about you and permit you to rot away'. Hardly pleasant.

Not to say that the castles of Europe were all gray eminence and no fun. In fact, the outer and inner walls of the castle were usually plastered and painted brightly, and the inner walls were often covered with tapestries to provide decoration and insulation for the cold stone walls. Natural lighting was available through large, glass-filled windows. While the technology of the day did not allow for large, single sheets of glass, smaller sheets were used in large numbers, bonded together with lead, to fill the windows.

Castles were also some of the earliest structures to feature a form of indoor plumbing. Most every living floor in a castle contained at least one privy room, called a garter room, which featured a wooden seat placed over a long shaft. This shaft carried waste from the living areas of the castle down into a nearby river or moat, or simply dumped it from an exit port built into the exterior of the outer wall. Glass was not used in the window of the garter room, to allow for better ventilation (smell wise), and to prevent the buildup of dangerous gasses in the room (a problem solved in the modern bathroom by the introduction of the water trap).

Castle construction continued until the 15th Century, when it fell into decline and new structures ceased to fill the dual defensive and governmental roles that earlier castles had occupied. Nobles took to building luxurious residences and palaces rather than fortress homes, and many of the older castles were abandoned and fell into disuse. Some of these disused castles were eventually destroyed by the ravages of time, which often included local villagers stealing stones from the construction to provide building material for their homes, churches, and walls (a fate that also befell many Roman structures following the fall of the Empire).

Two main factors contributed to the decline of castles in Europe. One was the discovery of gunpowder in the West, and the other was the changing political fortunes of the continent. Gunpowder made castles more or less worthless. Following years of constructions and great expense, the walls of a castle could be breached with a modest investment of black powder and personnel. This made the construction and staffing of traditional castles economically and strategically obsolete.

Furthermore, by the 15th Century, the political landscape of Europe had changed. No longer was the continent a patchwork of petty kingdoms, held together by feudal oaths that bound lesser nobles to greater ones. Central government had become possible due to development in communication, infrastructure and military technology, and networks of fortified lesser barons were no longer so necessary- or even desirable. A number of castles were destroyed by monarchs in order to prevent lesser nobles from getting ideas about setting off on military conquests, or starting rebellions. The greater political and social cohesion of the European states meant that frontier fortresses were no longer needed in order to pacify the countryside. Castles began to fall out of favor.

The last hurrah for true, old fashioned Medieval European castles came in Spain during the 15th Century, a by product of the Reconquista, the war to retake the Iberian peninsula from its Muslim rulers. Castles were built throughout Spain during this effort, in order to provide strongholds for the Christian and Muslim armies; the Castille region of Spain derives its name from its numerous castles and fortifications. Many of the castles built during this era were of mixed European and Moorish design, combining elements of the traditional European castle with Muslim architectural and artistic principles. This was true even for the castles built by Christian monarchs, which were often constructed by Muslim designers and laborers still residing in Spain.

While the structures built in Spain were still technically castles, those built during the 15th Century, like castles of similar vintage throughout Europe, already show signs of departure from the traditional model. They are much more elaborate and decorative than earlier castles, with elements of defense sometimes partially compromised in favor of design concerns. The Alcazar de Segovia is considered to be a high water mark for this decorative style of building castles, as well as a good example of a European castle incorporating Muslim design elements.

Castles as such largely disappeared from the military and political landscape, but continued to influence architecture and the popular imagination. There was a resurgence of interest in building castles- or at least in building luxury homes that looked like castles- in the 19th Century, particularly in England. The odd well-heeled eccentric in America has ensured that even us colonials and poor country relations have the chance to view a European-style castle (there's one less than two hours away from me- near Lexington, Kentucky!). Castles are now conceived of as being part of the history and heritage of the nations that they occupy, and many are now being preserved or restored.

Castle Defenses

And now, for the part that will be showing up in your next action movie or roleplaying game. Castle defenses were constructed in layers, becoming more and more deadly as one moved closer into the heart of the structure. The castle was meant to be a death trap for attackers, exacting a higher toll at every stage of the attack. While castles could and did fall on occasion, in general a competently manned castle would win in a battle against all but the most determined and diligent attackers.

The defense of a castle and its occupants began with the selection of its location. Natural barriers were used wherever possible to limit the directions from which the castle could be attacked. Rivers, cliffs, hills, and peninsulas were all used to this end. Trees and other obstructions outside the wall would be cut back and cleared away, to ensure that attackers would be afforded no cover outside the walls.

Castles were also built with withstanding siege in mind; every castle was provided with a water source, whether in the form of a freshwater spring, a well, or a cistern that collected rainwater. Livestock could be raised in the courtyards, and other supplies could be stored in store rooms in the lowest levels of the castle. Livestock could also be propelled from the castle on catapults, but this is only recommended when defending a castle from British comedy troupes.

If a castle had no natural defenses (and even if it did), man-made defenses were provided in the form of a moat. Contrary to popular myth, a moat was not necessarily a body of water, but rather was a ditch dug around the exterior of the wall. The moat was often very deep, and could be filled with either water or wooden spikes if local conditions or the lord's will so indicated. The bridge or gangway that crossed the moat could be retractable (the traditional drawbridge), or could be rigged to collapse altogether in the event of an attack.

The next layer of the castle defenses was its outer wall. The wall was usually built out of stone, bonded together with lime mortar. The walls were often built many feet thick, with an outside and inside 'casing' being built of fitted stone, and the interior filled with loose, unshaped stone and mortar. The wall was thickest at the bottom, and often featured a batter which jutted out from the base of the wall. The batter was constructed of hard stone, so that other stones dropped from the top of the wall would strike it and shatter, spraying shrapnel into the attacking hordes.

The top of the wall was often crenellated- consisting of a series of pillars (called merlons) and gaps (called crenels). An archer could duck behind the merlons to avoid enemy missile fire, and then step in front of one of the crenels to get a shot off. Also provided for the archers were numerous loopholes or arrow slits, narrow breaks in the wall that allowed archers to fire out from a position of safety. Loopholes were wider at the point where the archer stood, in order to allow them a range of targets. Each loophole had its own firing arc, designed with overlapping fields of fire to cover every possible point of attack against the castle. Loopholes faced both out of the wall and into the castle, and provided natural light to the interior of the wall in peace time. To give an idea of the scale of the firepower that castles could provide, Conwy castle in northern Wales had approximately 480 loopholes.

Built into the outer walls were towers, which in more sophisticated castles project out from the wall (that is, they form a 'bulge' in the outer wall). Towers were so positioned so that archers within them could fire on attackers at the base of the wall on either side of the tower, or at the base of other towers (they were often built in pairs). This discouraged sappers from attacking the base of the wall (as did such charming gifts as boiling oil, molten lead (found mostly in Victor Hugo novels), and loads of rocks).

The gateway of the castle was its weakest point, and so defenses were concentrated around this most likely point of attack. Numerous loopholes faced into the approach to the gateway, to pepper any incoming attackers with arrows and crossbow bolts (which could pierce heavy armor at the close ranges and limited confines of the gatehouse). A portcullis, a movable lattice-like gate that could be raised and lowered in a track (something like a modern garage door, but without joints in its structure), closed off the gate at its outermost point. The portcullis was usually made of wood (contrary to popular belief and cinematic depiction), and could be fired through by the castle's defenders.

If the portcullis was breached, the attackers were now into the gatehouse proper. They were now most likely faced with a set of heavy wooden doors, barred from within, that were five or more inches thick. More arrow slits faced into the gatehouse, exacting a toll on those who ventured within. Murder holes, gaps in the roof of the gatehouse, allowed stones, oil, excrement, and anything else the defenders desired to be poured down onto their enemies.

The inner gate was usually breached through the use of a battering ram, or by setting the gate on fire. This was far from foolproof; in some cases, the wind would turn against the attackers, and they would find the fire spreading from the gate to their battering ram or other equipment (this happened to the Romans at the siege of Masada). Assuming the gate could be successfully dispatched, the attacker now found himself inside one of the inner courtyards of the castle. There might be several layers of courtyards and thinner walls, segregated by the use of more heavy gates- which meant that the castle must be taken one section at a time, with a heavy cost at each breaching. However the castle was laid out internally, there were sure to be a great many more arrow slits facing into the inner courtyards. By breaching the outer walls and gates, the besiegers have won for themselves the right to stand in a large, open grassy or muddy area while men from inside and on top of the walls fire arrows, bolts, and stones down into them. Depending on how things have been going up until this point, and how many men the attacking general brought, the attackers are now either about to achieve total victory, or to be slaughtered in a most unsporting manner.

My money's on the guys with the castle. Youch.

Cas"tle (?), n. [AS. castel, fr. L. castellum, dim. of castrum a fortified place, castle.]


A fortified residence, especially that of a prince or nobleman; a fortress.

The house of every one is to him castle and fortress, as well for his defense againts injury and violence, as for his repose. Coke.

Our castle's strength Will laugh a siege to scorn. Shak.

⇒ Originally the mediaeval castle was a single strong tower or keep, with a palisaded inclosure around it and inferior buidings, such as stables and the like, and surrounded by a moat; then such a keep or donjon, with courtyards or baileys and accessory buildings of greater elaboration a great hall and a chapel, all surrounded by defensive walls and a moat, with a drawbridge, etc. Afterwards the name was retained by large dwellings that had formerly been fortresses, or by those which replaced ancient fortresses.

<-- Illustration of "Castle at Pierrefonds, France": -->

<caption>A Donjon or Keep, an irregular building containing the dwelling of the lord and his family; B C Large round towers ferming part of the donjon and of the exterior; D Square tower, separating the two inner courts and forming part of the donjon; E Chapel, whose apse forms a half-round tower, F, on the exterior walls; G H Round towers on the exterior walls; K Postern gate, reached from outside by a removable fight of steps or inclined plane for hoisting in stores, and leading to a court, L (see small digagram) whose pavement is on a level with the sill of the postern, but below the level of the larger court, with which it communicates by a separately fortified gateway; M Turret, containing spiral stairway to all the stories of the great tower, B, and serving also as a station for signal fire, banner, etc.; N Turret with stairway for tower, C; O Echauguettes; P P P Battlemants consisting of merlons and crenels alternately, the merlons being pierced by loopholes; Q Q Machicolations (those at Q defend the postern K); R Outwork defending the approach, which is a road ascending the hill and passing under all four faces of the castle; S S Wall of the outer bailey. The road of approach enters the bailey at T and passes thence into the castle by the main entrance gateway (which is in the wall between, and defended by the towers, C H) and over two drawbridges and through fortified passages to the inner court.</caption>

<-- end of illustration caption. -->


Any strong, imposing, and stately mansion.


A small tower, as on a ship, or an elephant's back.


A piece, made to represent a castle, used in the game of chess; a rook.

Castle in the air, a visionary project; a baseless scheme; an air castle; -- sometimes called a castle in Spain (F. Chateau en Espagne).

Syn. -- Fortress; fortification; citadel; stronghold. See Fortress.


© Webster 1913.

Cas"tle (?), v. i. [imp. & p. p. Castled (). p. pr. & vb. n. Castling (?).] Chess

To move the castle to the square next to king, and then the king around the castle to the square next beyond it, for the purpose of covering the king.


© Webster 1913.

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