The general opinion about the Boley Hill is that it is a Danish earthwork, thrown up by the Danes when they besieged the city in 885. But if our contention in Chapter IV. is just, the Danish fortifications were not mottes, nor anything like them; and (as has already been pointed out) the _Anglo-Saxon Chronicle_ indicates the nature of the fortress in this case by its expression, "they made a work around themselves";[626] that is, it was a circumvallation. Moreover, at Rochester the Danes would have had to pass under the bridge (which is known to have existed both in Roman and Saxon times) in order to get to the Boley Hill; and even if their ships were small enough to do this they would hardly have been so foolish as to leave a bridge in their possible line of retreat. It is therefore far more likely that their fastness was somewhere to the north or east of the city.[627] It is a noteworthy fact that up till very recently the Boley Hill had a special jurisdiction of its own, under an officer called the Baron of the Bully, appointed by the Recorder of the city. This appears to date from a charter of Edward IV. in 1460, which confirms the former liberties of the citizens of Rochester, and ordains that they should keep two courts' leet and a court of pie-powder annually on the Bullie Hill. The anonymous historian of Rochester remarks that it was thought that the baron represented the first officer under the governor of the castle before the court leet was instituted, to whose care the security of the Bullie Hill was entrusted.[628] This is probably much nearer the truth than the theory which would assign such thoroughly feudal courts as those of court leet and pie-powder to an imaginary community of Danes residing on the Boley Hill. When we compare the case of the Boley Hill with the somewhat similar cases of Chester and Norwich castles we shall see that what took place in Edward IV.'s reign was probably this: the separate jurisdiction which had once belonged to an abandoned castle site was transferred to the citizens of Rochester, but with the usual conservatism of mediæval legislation, it was not absorbed in the jurisdiction of the city. The value of Rochester at the time of the Survey had risen from 100_s._ to 20_l._[629] The increase of trade, arising from the security of traffic which was provided by William's castles on this important route, no doubt accounts in great measure for this remarkable rise in value.