Both varieties of the colonialist approach – the one which emphasises the European nature and origin of their achievements and the other that stressed the greater influence of the local inhabitants and the Levantine character of the Crusader states – came to the fore in the controversies over the source of the structures that are known as ‘concentric castles’ and of the counterweight trebuchet.

Rey's and Oman's colonialist approach

Emmanuel Guillaume Rey, who was the first to stress the concept of the merging of local and Frankish societies to form a joint colonialist one, was also the first to claim that the development of Crusader military architecture was influenced both by traditions of the Oriental-Byzantine fortress and the European motte and bailey.

Rey, however, considered the local contribution to be the more important of the two. He claimed that the principles underlying the construction of Crusader fortresses were those already formulated in the sixth century by Procopius. Obviously, he did not contend that the Franks were familiar with the writings of Procopius but he did believe that the Crusaders, on their way to the Holy Land, had been able to comprehend and appreciate the principles of the concentric type of castles they encountered in Byzantium, and that later they were capable of implementing and even perfecting them. The improved concentric castles were later ‘exported’ to their countries of origin.