Slighting

A slighting is the deliberate destruction, partial or complete, of a fortification without opposition. Sometimes, such as during the Wars of Scottish Independence and the English Civil War, the intention was to render the structure unusable as a fortress.

Middle Ages
In England during the Middle Ages adulterine (unauthorised) castles if captured by the king would usually be slighted. During the Wars of Scottish Independence King Robert the Bruce adopted a strategy of slighting Scottish castles to prevent them being occupied by the English. A strategy of slighting castles in the Levant was also adopted by the Mamelukes in their wars with the Crusaders.

Treaty of Edinburgh 1560
Under the terms of The concessions of Francis and Mary to the nobility and the people of Scotland and the Treaty of Edinburgh in July 1560, various fortified places were designated for demolition to prevent their use by French and English forces. These included the recent fortifications at Dunbar Castle, Leith and Eyemouth. On the island of Inchkeith a token garrison of 60 French soldiers were allowed to remain for a time. Inchkeith and Dunbar were finally slighted in 1567.

English Civil War
During the English Civil War many castles and fortified houses were slighted by the Parliamentarians to stop them being used by the Royalists. Most of the destruction was in Wales, the Midlands, and Yorkshire. The coastal fortifications were spared by the Commonwealth, as they might have been useful for hindering a Royalist or foreign invasion.

Burg Rheinfels
Situated on the left bank of the Rhine, Burg Rheinfels was started in 1245 by Count Diether V of Katzenelnbogen. By the late 17th century it was a fortress complex. It was the only Rhineland fortress to hold out against the French in the War of the Palatine Succession (1688–1697). During the French Revolutionary Wars, the left bank of the Rhine was annexed by the French Republic and incorporated into France as the department of Rhin-et-Moselle. Under the orders of the French Revolutionary government, Burg Rheinfels was slighted in 1797.