During the siege Wallace had kept the field, but Archie had, at his request, returned to his castle, which being but a day's march from Stirling, might at any moment be besieged. Several times, indeed, parties appeared before it, but Edward's hands were too full, and he could spare none of the necessary engines to undertake such a siege; and when Stirling at length fell he and his army were in too great haste to return to England to undertake another prolonged siege, especially as Aberfilly, standing in a retired position, and commanding none of the principal roads, was a hold of no political importance.

A short time afterwards, to Archie's immense grief, Sir William Wallace was betrayed into the hands of the English. Several Scotchmen took part in this base act, the principal being Sir John Menteith. Late historians, in their ardour to whitewash those who have for ages been held up to infamy, have endeavoured to show that Sir John Menteith was not concerned in the matter; but the evidence is overwhelming the other way. Scotch opinion at the time, and for generations afterwards, universally imputed the crime to him. Fordun, who wrote in the reign of Robert Bruce, Bowyer, and Langtoft, all Scotch historians, say that it was he who betrayed Wallace, and their account is confirmed by contemporary English writings. The Chronicle of Lanercost, the Arundel MSS., written about the year 1320, and the Scala Chronica, all distinctly say that Wallace was seized by Sir John Menteith; and finally, Sir Francis Palgrave has discovered in the memoranda of the business of the privy council that forty marks were bestowed upon the young man who spied out Wallace, sixty marks were divided among some others who assisted in his capture, and that to Sir John Menteith was given land of the annual value of one hundred pounds -- a very large amount in those days.