Dover had been a strong fortress for centuries, perched on its cliffs as high as an arrow can be shot, says one who may have been present at these events, and it had been recently strengthened with new work. William doubtless expected a difficult task, and he was correspondingly pleased to find the garrison ready to surrender without a blow, an omen even more promising than the victory he had gained over Harold. If William had given at Romney an example of what would follow stubborn resistance, he gave at Dover an example of how he proposed to deal with those who would submit, not merely in his treatment of the surrendered garrison of the castle, but in his payment of the losses of the citizens; for his army, disappointed of the plunder which would have followed the taking of the place by force, had burned the town or part of it. At Dover William remained a week, and here his army was attacked by a foe often more deadly to the armies of the Middle Ages than the enemies they had come out to fight. Too much fresh meat and unaccustomed water led to an outbreak of dysentery which carried off many and weakened others, who had to be left behind when William set out again. But these losses were balanced by reinforcements from Normandy, which joined him here or soon afterwards. His next advance was towards Canterbury, but it had hardly begun when delegations came up to meet him, bringing the submission of that city and of other places in Kent. Soon after leaving Dover the duke himself fell ill, very possibly with the prevailing disease, but if we may judge by what seems to be our best evidence, he did not allow this to interrupt his advance, but pushed on towards London with only a brief stop at any point.[1] Nor is there any certain evidence to be had of extensive harrying of the country on this march. His army was obliged to live on what it could take from the inhabitants, and this foraging was unquestionably accompanied with much unnecessary plundering; but there is no convincing evidence of any systematic laying waste of large districts to bring about a submission which everything would show to be coming of itself, and it was not like William to ravage without need. He certainly hesitated at no cruelty of the sort at times, but we can clearly enough see reasons of policy in most at least of the cases, which may have made the action seem to him necessary. Nearly all are instances either of defensive action or of vengeance, but that he should systematically ravage the country when events were carrying out his plan as rapidly as could be expected, we have no reason to consider in accordance with William's policy or temper. In the meantime, as the invading army was slowly drawing near to London, opinion there had settled, for the time at least, upon a line of policy. Surviving leaders who had been defeated in the great battle, men high in rank who had been absent, some purposely standing aloof while the issue was decided, had gathered in the city.