The men and women who came on the First Crusade and subsequently settled in the Levant came from areas which were already rich in castles and all of them would have been brought up in or near one. When they set about constructing fortifications to secure their new domains in the east, it was natural that they should draw on the experiences of their homelands.

In early medieval and Carolingian times, fortifications in western Europe had for the most part been public or group strongholds, built for defence by and protection of comparatively large numbers of people. The most obvious examples of these were the Roman walls, which still encircled many of the small cities of the time. The legacy of Roman military architecture in the west was much more obvious to eleventh-century men than it is to us today and they did not have to look to North Africa or the Middle East to see examples of the classical tradition; they only had to look at the walls of Senlis, Le Mans or Pevensey to see high stone walls with projecting towers ranged at intervals along them.

New fortifications were also constructed in these centuries. In many cases these were promontory forts, where the man-made defences cut off a natural promontory, either on the coast, or overlooking a river valley or simply on a spur of a hill. Frequently such promontory forts were defended by one or more earth banks and ditches but stone walls were not unknown.

From the early seventh century these large-scale fortifications were gradually supplemented and replaced by castles with a much more restricted perimeter…