Crenellation

A battlement in defensive architecture, such as that of city walls or castles, comprises a parapet (i.e., a defensive low wall between chest-height and head-height), in which rectangular gaps or indentations occur at intervals to allow for the discharge of arrows or other missiles from within the defences. These gaps are termed "crenels" (also known as carnels, embrasures, or wheelers), and the act of adding crenels to a previously unbroken parapet is termed crenellation. Thus, a defensive building might be designed and built with battlements, or a manor house might be fortified by adding battlements, where no parapet previously existed, or cutting crenellations into its existing parapet wall. The solid widths between the crenels are called merlons (also cops or kneelers). A wall with battlements is said to be crenelated or embattled. Battlements on walls have protected walkways (chemin de ronde) behind them. On tower or building tops, the (often flat) roof is used as the protected fighting platform.

The term originated in about the 14th century from the Old French word batailler, "to fortify with batailles" (fixed or movable turrets of defence). The word crenel derives from the ancient French cren (modern French cran), Latin crena, meaning a notch, mortice or other gap cut out often to receive another element or fixing; see also crenation. The modern French word for crenel is créneau, also used to describe a gap of any kind, for example a parking space at the side of the road between two cars, interval between groups of marching troops or a timeslot in a broadcast.

In medieval England a licence to crenellate granted the holder permission to fortify their property. Such licences were granted by the king, and by the rulers of the counties palatine within their jurisdictions, e.g. by the Bishops of Durham and the Earls of Chester and after 1351 by the Dukes of Lancaster. The castles in England vastly outnumber the licences to crenellate. Royal pardons were obtainable, on the payment of an arbitrarily determined fine, by a person who had fortified without licence. The surviving records of such licences, generally issued by letters patent, provide valuable evidence for the dating of ancient buildings. A list of licences issued by the English Crown between the 12th and 16th centuries was compiled by Turner & Parker and expanded and corrected by Philip Davis and published in The Castle Studies Group Journal.

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