Harry appears to think that Menteith was Constable of Dumbarton in Wallace's interest; and the dramatic remonstrance he puts into Menteith's mouth is sufficiently transparent. However, it elicits from Sir Aymer a promise that Wallace's life shall be safe, and that Edward will be satisfied if his great enemy be securely lodged in prison. On this promise, Menteith consents. True or untrue, it is the only decent plea that has ever been suggested on Menteith's behalf; and even then it disgraces his intelligence. Harry further indicates that Menteith, after all, delayed somewhat in the execution of the project. He says that Edward wrote to Menteith privately, and 'prayed him to haste.' The infamous wretch sorely needs the full benefit of Harry's palliations.

Menteith proceeded to carry out his scheme. Harry says he got 'his sister's son' to attach himself to Wallace's personal following, with full instructions for the betrayal. The youth was to inform Menteith of Wallace's movements, so as to enable him to effect the capture under the most favourable conditions. This subordinate tool is said to have been named Jack Short: the authority of Langtoft is usually given, but mistakenly; it is not Langtoft, but Langtoft 'illustrated and improved' by Robert of Brunne, that mentions 'Jack Short his man' as the instrument of Wallace's betrayal, adding by way of explanation, that 'Jack's brother had he slain.'

The desired opportunity soon offered. According to Harry, Bruce, in reply to an invitation to come and claim the crown, informed Wallace that he would devise an excuse for leaving the English court, and endeavour to meet him on Glasgow Moor on the first night of July. Attended only by the ever-faithful Kerly and the treacherous emissary of Menteith, Wallace rode out on several evenings from Glasgow to Robroyston, in expectation of Bruce. On 'the eighth night,' Menteith received notice, and with sixty sworn men—'of his own kin, and of kinsmen born'—he hurried to the scene. About midnight, Wallace and Kerly went to sleep—a very unlikely thing for Kerly to do in the circumstances. The traitorous attendant then is said to have removed their arms, and given the signal to Menteith. Kerly was instantly despatched. Wallace started up, and, missing his arms, defended himself with his hands. Menteith then came forward, and represented that resistance was in vain, the house being surrounded by English troops; that the English really did not wish to kill him; and that he would be safe under his protection in his (Wallace's) own house in Dumbarton Castle. Wallace thought that Menteith, his gossip—nay, 'his gossip twice' (for Major, in consonance with Harry, records that Wallace had stood godfather to two of Menteith's children)—might be trusted; still he made him swear. As Harry remarks, 'That wanted wit; what should his oaths avail any more, seeing he had been long forsworn to him?' The oath taken, Wallace resigned his hands to the 'sure cords' of Menteith.

As they fared forth, Wallace saw no Southrons, and he missed Kerly—to him convincing signs of betrayal. Still Menteith protested that the sole intention was to keep their prisoner in security; there was no design against his life. The truth, however, was at once evident. Menteith did not proceed to Dumbarton, but took his way right south with all speed, 'aye holding the waste land,' for 'the traitors durst not pass where Scotsmen were masters,' and it was essential to their purpose to gain time on Wallace's men, and to baffle the certain pursuit. On the south side of 'Solway sands,' Menteith delivered Wallace to Sir Aymer de Valence and Sir Robert de Clifford, who conducted him 'full fast' to Carlisle, where they threw him into prison. His real custodian, however, appears to have been Sir John de Segrave, the Warden south of Forth.

Such writers as exculpate Menteith from participation in the capture of Wallace lie under the obligation of explaining the following facts. There still exists a document that looks like a memorandum of business for Edward's parliament or council. It notes that 40 marks are to be given to the vallet who spied out (espia) William Wallace; that 60 marks are to be given to the others, and that the King desires they shall divide the money among them; and that £100 in land is to be given to John de Menteith. Again: shortly after the middle of September, when the Scots commissioners attended the English parliament for the special purpose of agreeing to regulations for the settlement of Scotland, nine, instead of ten, appeared; and in place of Earl Patrick, who was the absent member, Sir John de Menteith 'by the King's command was chosen.' By one of the regulations then agreed to, Sir John de Menteith was confirmed in the governorship of Dumbarton Castle. Further: on November 20, 1305, a signal mark of royal favour is recorded with peculiar emphasis. At the request of 'his faithful and loyal John de Menteith,' Edward commands his Chancellor to issue letters of protection and safe-conduct in favour of certain burgesses of St. Omer passing with their goods and merchandise through his dominions; the letters to be framed in such especial form as John de Menteith shall wish 'in reason,' to last for two or three years as pleases him most. The Chancellor is to deliver them without delay to Menteith, and to no other; for the King has granted them to him 'with much regret,' and would have given them to no other than himself. And finally, on June 16, 1306, Edward commands Sir Aymer de Valence to deliver to Sir John de Menteith the temporality of the bishopric of Glasgow towards Dumbarton, during pleasure; and on the same date he informs Sir Aymer that he has ordered the Chancellor and Chamberlain to prepare a charter granting the Earldom of the Lennox to Sir John de Menteith, 'as one to whom he is much beholden for his good service, as Sir Aymer tells him, and he hears from others,' and he commands Sir Aymer to give him seisin. Harry may have mixed up the facts a little, but it is plain that he has got hold of the main thread. Apart from the capture of Wallace, it is simply incredible that Menteith's services would have been deemed so markedly valuable in the eyes of the English King.

Having apprised Edward of the capture of his great enemy, Valence and Clifford brought Wallace on to London. Harry says Valence and Clifford, but no doubt he ought to have said Sir John de Segrave; at any rate, Wallace was in the custody of Segrave on August 18. The news of Wallace's coming had spread far and wide, and as the cavalcade approached the capital, it was met by a multitude of men and women, curious to gaze upon the rebellious savage—says Stow, 'wondering upon him.' The illustrious captive was lodged in the house of Alderman William de Leyre, in the parish of Allhallows Staining, at the end of Fenchurch Street. It may seem strange that he was not taken to the Tower. In any case, it is in the last degree improbable that the fact points to any intention of Edward to make a final attempt to secure Wallace's submission to his grace. There is certainly more probability in Carrick's conjecture, that the reason was 'the difficulty which the party encountered in making their way through the dense multitudes who blocked up the streets and lanes leading to the Tower.' Anyhow, it is a point of very subordinate interest. The date of the arrival was Sunday, August 22.

No time was lost. Everything was in readiness. The very next morning, Monday, August 23, 1305, Wallace was conducted on horseback from the City to Westminster, to undergo the farce of trial. Sir John de Segrave was in command of the escort, and with him there rode the Mayor, Sheriffs, and Aldermen of London, followed by a great number of people, on horseback and on foot. Arrived at Westminster Hall, Wallace was placed on the bench on the south side. It is said that, as he sat there awaiting his doom, he was crowned with a garland of laurel leaves. The popular English fancy absurdly associated this strange procedure with an alleged assertion of Wallace's in times past, to the effect that he deserved to wear a crown in that Hall. Some writers regard it as a mark of derision. Llewelyn's head had been exposed on the battlements of the Tower crowned with a wreath of ivy—said to be in fulfilment of a prophecy of Merlin's. Sir Simon Fraser is said, in the ballad, to have been drawn through the streets to the gallows with 'a garland on his head after the new guise'; though Langtoft says Fraser's head was fixed on London Bridge 'without chaplet of flowers,' as if the omission were a noticeable breach of custom. It is a mistake, then, to suppose that the garland was a special insult to Wallace. It may have marked the satisfaction of victory over a notable enemy. It may be taken as the fillet of the destined victim.

The Commissioners appointed to try Wallace were Sir John de Segrave; Sir Peter Malory, the Lord Chief Justice; Ralph de Sandwich, the Constable of the Tower; John de Bacwell (or Banquelle), a judge; and Sir John le Blound (Blunt), Mayor of London. They had been appointed by Edward on August 18. They were all present. The indictment was comprehensive, charging sedition, homicide, spoliation and robbery, arson, and various other felonies. The charge of sedition or treason was based on Edward's conquest of Scotland. On Balliol's forfeiture, he had reduced all the Scots to his lordship and royal power; had publicly received homage and fealty from the prelates, earls, barons, and a multitude of others; had proclaimed his peace throughout Scotland; and had appointed wardens, his lieutenants, sheriffs, and others, officers and men, to maintain his peace and to do justice. Yet this Wallace, forgetful of his fealty and allegiance, had risen against his lord; had banded together a great number of felons, and feloniously attacked the King's wardens and men; had, in particular, attacked, wounded, and slain William de Hazelrig, Sheriff of Lanark, and, in contempt of the King, had cut the said Sheriff's body in pieces; had assailed towns, cities, and castles of Scotland; had made his writs run throughout the land as if he were Lord Superior of that realm; and, having driven out of Scotland all the wardens and servants of the Lord King, had set up and held parliaments and councils of his own. More than that, he had counselled the prelates, earls, and barons, his adherents, to submit themselves to the fealty and lordship of the King of France, and to aid that sovereign to destroy the realm of England. Further, he had invaded the realm of England, entering the counties of Northumberland, Cumberland, and Westmoreland, and committing horrible enormities. He had feloniously slain all he had found in these places, liegemen of the King; he had not spared any person that spoke the English tongue, but put to death, with all the severities he could devise, all—old men and young, wives and widows, children and sucklings. He had slain the priests and the nuns, and burned down the churches, 'together with the bodies of the saints and other relics of them therein placed in honour.' In such ways, day by day and hour by hour, he had seditiously and feloniously persevered, to the danger alike of the life and the crown of the Lord King. For all that, when the Lord King invaded Scotland with his great army and defeated William, who opposed him in a pitched battle, and others his enemies, and granted his firm peace to all of that land, he had mercifully had the said William Wallace recalled to his peace. Yet William, persevering seditiously and feloniously in his wickedness, had rejected his overtures with indignant scorn, and refused to submit himself to the King's peace. Therefore, in the court of the Lord King, he had been publicly outlawed, according to the laws and customs of England and Scotland, as a misleader of the lieges, a robber, and a felon.

It was laid down as not consonant with the laws of England, that a man so placed beyond the pale of the laws, and not afterwards restored to the King's peace, should be admitted either to defend himself or to plead. Still it is recorded that Wallace, whether regularly or irregularly, did reply to Sir Peter Malory, denying that he had ever been a traitor to the English King. He is also said to have acknowledged the other charges preferred. There are allegations of wanton and extravagant misdeeds that undoubtedly merited denial, and could not have been positively acknowledged by Wallace. It may be that he considered it futile to raise any further objection, and heard the charges with the contempt of silent indifference.

Sentence was pronounced: