received view has now been challenged from two directions – from the perspectives of the strategies involved, and a new interpretation of the coinage of King Alfred. The order of citation of the individual burhs in the document, in a clockwise circuit around Wessex rather than on a shire by shire basis, indicates that at the time of the original composition of the document all the burhs were seen as being part of a single system. The defining characteristic of this system is that these fortified sites would have all been built at one occasion to serve a single strategic end, in that the functions of all the individual components of the system complemented the functions of each of the others. It follows that it cannot have originated, for instance, as a core number to which others were added at a later date. By the early 10th century this system was already long out of date and overtaken by events. It is not likely therefore to have survived as a viable and effective system to be recorded as such in the Burghal Hidage after 914. There would, furthermore, have been no reason to add Buckingham to a system which by 914 was already redundant in the rapidly evolving political situation of the times. There are therefore good grounds for suggesting that the system (and therefore the document which describes it) is considerably earlier in date. Political and military context It has long been recognised that the system of burhs recorded in the Burghal Hidage was the creation of King Alfred, the received view being that they were in place by the time of the second Viking invasions in the 890s (based on the evidence in the Anglo-Saxon Chronicle of the existence of garrisons in many of them by this time), and that most of them were constructed in the 880s. However, the fact that nearly half the number of hides in the system were allocated to burhs on the northern border of Wessex with Mercia suggests a context for the creation of this system in the period when Mercia was occupied and controlled by the Vikings. This was the situation in the period from 874, when the Vikings at Repton installed Ceolwulf (II) as king of Mercia to replace Burgred. The most probable context on strategic grounds is in the short period between 877 and 879, when Mercia was partitioned