A keep which was built on a square plan, possessing advantages over the wooden donjon design which proceeded it, such as; they could not be fired, they could be built to a greater height, and because of their height they did not need the same concentration of defenders as was needed for the defence of the lower earth and timber walls. Their disadvantages were that their square corners could easily be attacked with a bore or by undermining, and the square shape also limited the field of fire. The development of the polygonal and round keeps offset most of these faults. See keep, polygonal keep.
|