There is no other corresponding contrast of men and emptiness that I know of in Europe. The great towns lie, enormous, pullulating, millioned in the plains on either side; they push their limbs up far into the valleys. Between them, utterly deserted, you have these miles and miles of bare upland, like the roof of a house between two crowded streets. Merely to cross the Pennines, driving or on foot, is sufficient to teach one this. To go the length of the hills along the watershed from the Peak to Crossfell (few people have done it!) is to get an impression of desertion and separation which you will match nowhere else in travel, nowhere else, at least, within touch and almost hearing of great towns. The sea also was here more of a barrier than a bond. Ireland--not Roman, and later an enemy--lay over against that shore. Its ports (save one) silted. Its slope from the shore was shallow: the approach and the beaching of a fleet not easy. Its river mouths were few and dangerous. This triangle of Lancashire, so cut off from the west and from the east, had for its base a barrier that completed its isolation. That barrier was the marshy valley of the Mersey. It could be outflanked only at its extreme eastern point, where the valley rises to the hundred-foot contour line. From that point the valley rises so rapidly within half a dozen miles into the eastern hills that it was dry even under primitive conditions, and the opportunity here afforded for a passage is marked by the topographical point of Stockport. By that gate the main avenues of approach still enter the county. Through this gap passed the London Road, and passes to-day the London and North-Western Railway. It was this gate which gave its early strategic importance to Manchester, lying just north of it and holding the whole of this corner. Historians have noted that to hold Manchester was ultimately to hold Lancashire itself. It was not the industrial importance of the town, for that was hardly existent until quite modern times: it was its strategic position which gave it such a character. The Roman fort at the junction of the two rivers near Knott Mill represented the first good defensible position commanding this gate upon the south-east. To enter the county anywhere west of the hundred-foot contour and the Mersey Valley was, for an army deprived of modern methods, impossible: a little organized destruction would make it impossible again.