The new type of keepless castle never entirely displaced the old keep-and-bailey type. We have already seen that keeps of the old sort continued to be built till the end of the Middle Ages. Hawarden Castle has a good example of a 14th-century round keep; Warkworth a most remarkable specimen of the 15th, the plan being a square tower with polygonal turrets set on each face.[1202] In France and Germany also the old type appears to have persisted.[1203] We have already trespassed beyond the limits of our subject; but as we offer this chapter more as a programme of work than as a categorical outline, we trust it may not be without use to the student who may feel disposed to take up this much-neglected subject. A few words must yet be said about the state of the law relating to castles. Nothing explicit has come down to us on this subject from the 11th century in England, but it is clear that the feudal system which William introduced, and which required that all lands should revert to the king on the death of the holder, forbade the building of any castle without the king's license, and, further, allowed only a life tenure in each case. The Council of Lillebonne in 1080 had laid it down in express terms that no one should build a castle in Normandy without the permission of the duke;[1204] and William, after his great victory over his revolted barons, had enforced the right of garrisoning their castles. He was not able to do this in England, while he must have desired to check the building of private castles as far as possible. On the other hand, he had to face the dilemma that no Norman land-holder would be safe in his usurped estates without the shelter of a castle. In this situation we have the elements of the civil strife which burst forth in Stephen's reign, and which was ended by what we may call the anti-castle policy of Henry II.[1205] The rights secured by this able king were often recklessly sold by his successors, but in the reign of Henry III. it was evidently illegal even to fortify an ordinary house with a ditch and stockade without royal permission.[1206] * * * * *