Castles

Castles have played an important military, economic and social role in Great Britain and Ireland since their introduction following the Norman invasion of England in 1066. Although a small number of castles had been built in England in the 1050s the Normans began to build motte and bailey and ringworks castles in large numbers to control their newly occupied territories in England and the Welsh Marches. During the 12th century the Normans began to build more castles in stone, with characteristic square keeps that played both military and political roles. Royal castles were used to control key towns and the economically important forests, while baronial castles were used by the Norman lords to control their widespread estates. David I invited Anglo-Norman lords into Scotland in the early 12th century to help him colonise and control areas of his kingdom such as Galloway; the new lords brought castle technologies with them and wooden castles began to be established over the south of the kingdom. Following the Norman invasion of Ireland in the 1170s, under Henry II, castles were established there too.

Castles continued to grow in military sophistication and comfort during the 12th century, leading to a sharp increase in the complexity and length of sieges in England. While in Ireland and Wales castle architecture continued to follow that of England, after the death of Alexander III the trend in Scotland moved away from the construction of larger castles towards the use of smaller tower houses. The tower house style would also be adopted in the north of England and Ireland in later years. In North Wales Edward I built a sequence of militarily powerful castles after the destruction of the last Welsh polities in the 1270s. By the 14th century castles were combining defences with luxurious, sophisticated living arrangements and heavily landscaped gardens and parks.

Many royal and baronial castles were left to decline, so that by the 15th century only a few were maintained for defensive purposes. A small number of castles in England and Scotland were developed into Renaissance Era palaces that hosted lavish feasts and celebrations amid their elaborate architecture. Such structures were, however, beyond the means of all but royalty and the richest of the late-medieval barons. Although gunpowder weapons were used to defend castles from the late 14th century onwards it became clear during the 16th century that, provided artillery could be transported and brought to bear on a besieged castle, gunpowder weapons could also play an important attack role. The defences of coastal castles around the British Isles were improved to deal with this threat, but investment in their upkeep once again declined at the end of the 16th century. Nevertheless, in the widespread civil and religious conflicts across the British Isles during the 1640s and 1650s, castles played a key role in England. Modern defences were quickly built alongside existing medieval fortifications and, in many cases, castles successfully withstood more than one siege. In Ireland the introduction of heavy siege artillery by Oliver Cromwell in 1649 brought a rapid end to the utility of castles in the war, while in Scotland the popular tower houses proved unsuitable for defending against civil war artillery - although major castles such as Edinburgh put up strong resistance. At the end of the war many castles were slighted to prevent future use.

Military use of castles rapidly decreased over subsequent years, although some were adapted for use by garrisons in Scotland and key border locations for many years to come, including during the Second World War. Other castles were used as county jails, until parliamentary legislation in the 19th closed most of them down. For a period in the early 18th century castles were shunned in favour of Palladian architecture, until they re-emerged as an important cultural and social feature of England, Wales and Scotland and were frequently "improved" during the 18th and 19th centuries. Such renovations raised concerns over their protection so that today castles across the British Isles are safeguarded by legislation. Primarily used as tourist attractions, castles form a key part of the national heritage industry. Historians and archaeologists continue to develop our understanding of British castles, while vigorous academic debates in recent years have questioned the interpretation of physical and documentary material surrounding their original construction and use.