The victorious Danes, naturally, proceeded to wreak special vengeance on such obstinate foes. The county was ravaged with a ferocity even beyond the usual Danish harryings, and Cambridge itself was sacked and burnt. When it arose from its ashes, in the quieter days of the Danish Canute, the first "King of England," (his native predecessors having been Kings "of the English,") it was organised, Danish fashion, into ten Wards, each with its own "Lawman." In the reign of Edward the Confessor, it had, as we have seen, 400 dwelling-houses (_masurae_), not urban cottages closely packed in rows, but mostly tenements of the farmhouse type, each with its farmyard, the abodes of the husbandmen who owned and tilled the Common Fields of the town. This number of houses shows Cambridge to have been at this time an important place, equal in population to a whole average "Hundred," with its ten villages; and as such we find it counted for legal purposes under the Norman and Plantagenet dynasties. But its Common Fields were by no means proportionately extensive,[3] so that many of the inhabitants must already have depended upon trade for their living. [Footnote 3: An ordinary "Hundred" contained an area some five miles square, instead of the five square miles which was that of old Cambridge.] If Cambridge fared ill at the hands of the Danes, it fared little better at those of the Normans. William the Conqueror made the place his headquarters in his operations against Hereward's "Camp of Refuge" at Ely. This resulted in the ruin of fifty-three out of the 400 houses, besides twenty-seven more pulled down to make room for his new Castle, which with its outworks and huge central keep occupied the greater part of the old Roman site to the west of the Bridge. The loss of these eighty houses probably brought down the population to little over 2,000 souls. Even with this reduction, however, the town might still claim to rank in the first class of English cities at the time; and this is shown by the growth of a Jewry within its walls, in the area bounded by St. John's College, Trinity College, and Bridge Street. For the Jews, (who first came into England as camp-followers of the Norman invaders,) naturally struck for the wealthier towns in which to form their settlement. As the place grew in importance Religious Houses began rapidly to spring up in and around it; the first being the great Augustinian Abbey of Barnwell, founded by Picot, the Sheriff of Cambridge under William the Conqueror.