Interactions Between Orient and Occident in Fortification at the time of the Crusades. During the crusades, fortification constituted an exceptional filled of exchanges, implying many influence spheres, scattered in time and in space. In the 12th century, genesis of the crusader fortification resulted from the synthesis of several models, from antique fortification to european fortification, or contemporary oriental fortification, byzantine as well as muslim. In the 13th century, while import in the Holy Land of the capetian fortification developed in France constituted the essential phenomenon, influence of byzantine and antique fortifications on the crusader fortification kept up, and important exchanges with muslim fortification are att...