But the system which Wallace had organised for the emancipation of his country, was not liable to any material derangement, in consequence of the defection of a few timid and interested barons. It is true, the desertion of such men as Sir William Douglas must have occasioned him considerable regret, being thereby prevented from meeting the enemy openly in the field, with such an equality of force as would have insured success. This feeling, however, did not retard his exertions, but rather stimulated him to fresh undertakings; for we find that he shortly afterwards surprised and garrisoned the Castle of Dunotter. Tyber,[109] or Tibber, on the banks of the Nith, he also took and destroyed. Forfar, Brechin and Montrose, were either taken, or deserted by their garrisons on his approach. Aberdeen, which the enemy set on fire, and then retreated to their ships, afterwards fell into his hands. He then led his troops against the Castle of Dundee, and had already made considerable progress in the siege of that strong-hold, when he was apprised of the advance of an English army under the Earl of Warren, and Cressingham the treasurer. Edward, dissatisfied with the imperfect measures which had been taken for the suppression of the Scottish revolt, and irritated by the accounts which were daily received of the operations of the insurgents, had despatched peremptory orders for Warren to proceed in person to the North. He also directed his writs to the Bishop and Sheriff of Aberdeenshire, commanding them to adopt strong and effectual means for extinguishing the flame of rebellion within the boundaries of their jurisdiction. They were likewise required to furnish whatever supplies might be wanted by William de Warren[110] for the defence of the Castle of Urquhart, a strong and extensive fortress on the banks of Loch Ness, of which he was governor. Warren was also ordered to be at his post, and fully prepared to meet any attempt of the enemy. On learning the movements of the English, Wallace collected those of the burgesses of Dundee who were able to bear arms, and, placing them under the command of their townsman, Sir Alexander Scrymgeour, enjoined them, at the peril of “lyf and lyme,”[111] to continue the siege. He then retired, with his followers, who were now considerably increased, to watch the motions of the advancing army. In cases of invasion, a favourite plan adopted by the Scots for the defence of their country, was to convey their cattle and other valuables to the more inaccessible districts north of the Forth. By this measure, they not only secured their own suppplies, but, by depriving their enemies of the means of subsistence, compelled them to an early retreat as the only resource against the miseries of starvation. On the present occasion the usual precaution was not omitted.[112]