ABSTRACT
Jacques Ellul divides the medieval period in the West into two distinct phases, the first of which actually culminated during the eleventh century. The earlier phase had been characterized by shrinking populations, forest encroaching upon pasture, regressive economy with declining commerce and partial disappearance of money. In the eleventh century the ancient art of fortification was being rediscovered and shaped to meet the conditions of the Medieval world. Many of the medieval cities had passed through long and often glorious earlier phases — Rome, Ravenna, Constantinople, Cordova, Paris, London — and it is interesting therefore to find one that had arisen out of the conditions of the age, and in virtue of its special advantages was destined to surpass all its rivals, exercising an authority that transcended its municipal limits and made it an influential world power.
