The military efficiency of the mercenary of the thirteenth century was, however, only a development of that of the ordinary feudal cavalier. Like the latter, he was a heavily-armed horseman; his rise did not bring with it any radical change in the methods of war. Though he was a more practised warrior, he still worked on the old system--or want of system--which characterised the cavalry tactics of the time. The final stage in the history of mercenary troops was reached when the bands which had served through a long war instead of dispersing at its conclusion, held together, and moved across the continent in search of a state which might be willing to buy their services. But the age of the ‘Great Company’ and the Italian Condottieri lies rather in the fourteenth than the thirteenth century, and its discussion must be deferred to another chapter. In the whole military history of the period the most striking feature is undoubtedly the importance of fortified places, and the ascendancy assumed by the defensive in poliorcetics. If battles were few, sieges were numerous and abnormally lengthy. The castle was as integral a part of feudal organization as the mailed knight, and just as the noble continued to heap defence after defence on to the persons of himself and his charger, so he continued to surround his dwelling with more and more fortifications. The simple Norman castle of the eleventh century, with its great keep and plain rectangular enclosure, developed into elaborate systems of concentric works, like those of Caerphilly and Carnarvon. The walls of the town rivalled those of the citadel, and every country bristled with forts and places of strength, large and small. The one particular in which real military capacity is displayed in the period is the choice of commanding sites for fortresses. A single stronghold was often so well placed that it served as the key to an entire district. The best claim to the possession of a general’s eye which can be made in behalf of Richard I. rests on the fact that he chose the position for Château Gaillard, the great castle which sufficed to protect the whole of Eastern Normandy as long as it was adequately held.