This isolation was in great part due to physical causes. What is now the busy West Riding was then mainly a vast tract of moor and woodland, stretching from Wakefield to the Peak and from the Westmoreland hills to the sources of the Don; while further east, the district between the lower course of the Don and that of the Trent was one wide morass. Such obstacles were still strong enough to hinder, though not to bar, the intercourse of Yorkshire with mid-England. The only safe line of communication was the Foss Way, which struck across the central plain and along the eastern side of the Trent valley to Lincoln, and thence turned north-westward to cross the Trent and wind round between forest and fen to York. Lincoln was thus the chief station on the highway between York and the south. Under the Norman rule the city had risen to a new importance. Two of its quarters had been entirely transformed; the south-western was now covered by a castle, and the south-eastern by a cathedral church. Neither building was the first of its kind which had occupied the spot. Few sites in England could have been more attractive to a soldier’s eye than the crest of the limestone ridge descending abruptly to the south into a shallow sort of basin, watered by the little river Witham, and on the west sloping gradually down to a broad alluvial swamp extending as far as the bank of the Trent. The hundred and sixty-six houses which the Conqueror swept away to make room for his castle[95] were but encroachments on an earlier fortification, a “work” of mounds and earthen ramparts of the usual old English type, which now served as a foundation for his walls of stone.[96] To the ardent imagination of the medieval Church, on the other hand, the rocky brow of Lincoln might well seem to cry out for a holier crown, and a church of S. Mary was already in existence[97] on the site where Bishop Remigius of Dorchester, forsaking his lowly home in the valley of the Thames, reared his bishopstool amid the foundations of that great minster of our Lady whose noble group of towers now rises on the crest of the hill as a beacon to all the country round.[98] But there were other reasons for the translation of the bishopric than those of sentiment or of personal taste. Of the vast Mid-Anglian diocese, which stretched from the Thames to the Humber, Lincoln was beyond all comparison the most important town. Even in Roman times the original quadrangular enclosure of Lindum Colonia had been found too small, and a fortified suburb had spread down to the left bank of the Witham. During the years of peace which lasted from the accession of Cnut to that of William, the needs of an increasing population, as we have seen, covered the site of the older fortress with dwellings: when these were cleared away at William’s bidding, their exiled inhabitants found a new home on a plot of hitherto waste ground beyond the river; and a new town, untrammelled