The Age of Disorder ; Feiuialism 389 But as the Roman Empire grew weaker and the disorder Early castles caused by the incoming barbarians became greater, the various counts and dukes and even other large landowners began to build forts for themselves, usually nothing more than a great round mound of earth surrounded by a deep ditch and a wall made of stakes interwoven with twigs. On the top of the mound was a wooden fortress, surrounded by a fence or palisade, Fig. 154. Medieval Battering-ram This is a simple kind of battering-ram, which was trundled up to the walls of a besieged casde and then swung back and forth by a group of soldiers, with the hope of making a breach. The men were often protected by a covering over the ram similar to the one at the foot of the mound. This was the type of " castle " that prevailed for several centuries after Charle- magne's death. There are no remains of these wooden castles in existence, for they were not the kind of thing to last very long, and those that escaped being burned or otherwise destroyed, rotted away in time. About the year iioo these wooden buildings began to be re- improved placed by great square stone towers. This was due to the fact ^t^ck lead that the methods of attacking castles had so changed that wood gt^ng^to^^^g was no longer a sufficient protection. The Romans when they about uoo besieged a walled town were accustomed to hurl great stones and heavy-pointed stakes at the walls and over them. They had ingenious machines for this purpose, and they also had ways of
