Amidst the pomp of the gallant ceremonial, Edward's mind was keenly bent upon the business of the expedition. Writing to Valence on May 24, he desires 'that some good exploit be done, if possible, before his arrival.' Two days later (May 26), he is delighted to hear that Valence, then at Berwick, is ready to operate against the enemy, and urges him to strike at them as often as possible, and in concert with the forces at Carlisle. As regards 'the request by some for a safe-conduct for the Bishop of St Andrews,' Valence, he orders, 'will neither give, nor allow any of his people to give such.' The Bishop, if he pleases, may come to the King's faith, and receive his deserts. Let Valence take the utmost pains to secure the Bishop's person, and also the person of the Bishop of Glasgow; and let him send frequent news of his doings.
Valence had a stroke of luck. On June 8, Edward 'is very much pleased' to learn from him 'that the Bishop of Glasgow is taken, and will soon be sent to him.' The Bishop had been taken in arms on the recapture of Cupar Castle by the English. A week later (June 16), Edward informs Valence that 'he is almost as much pleased as if it had been the Earl of Carrick,' and directs him to send the Bishop 'well guarded' to Berwick, 'having no regard to his estate of prelate or clerk.' The order was executed without any undue tenderness to the Bishop. The Bishop of St Andrews, however, was still at large. 'I understand from many,' wrote Edward to Valence in the letter of June 8, 'that the Bishop of St Andrews has done me all the mischief in his power, for, though chief of the Guardians of Scotland appointed by me, he has joined my enemies.'
As yet the edge of Edward's appetite was but whetted. On June 12, he 'is well pleased to hear that Valence has burned Sir Simon Fraser's lands in Selkirk Forest,' and commands him 'to do the same to all enemies on his march, including those who turned against him in this war of the Earl of Carrick, and have since come to his peace as enemies and not yet guaranteed; and to burn, destroy, and waste their houses, lands, and goods in such wise that Sir Simon and others may have no refuge with them as heretofore.' At the same time, Valence is to spare and honour the loyal, and in particular to compliment the foresters of Selkirk on their loyal and painful service. In successive letters he reiterates the caution to beware of surprise and treason, and his anxiety for constant news.
Still more vindictive is his tone on June 19. He commands Valence to burn, destroy, and strip the lands and gardens of Sir Michael de Wemyss's manors, 'as he has found nor good speech nor good service in him,' and this for an example to others. Likewise, to do the same, or worse, if possible, to the lands and possessions of Sir Gilbert de la Haye, to whom the King did great courtesy when he was last in London, but now finds he is a traitor': the King will make up the loss to the persons to whom he has granted his lands!
Meantime the Pope made his voice heard. On May 6, he had written to Edward, promising to send a nuncio to deal with the Bishop of Glasgow and others; and on May 11, he had strongly denounced to the Archbishop of York the assumption of the Bishop, desiring him to order the culprit peremptorily to come to his Holiness at Bordeaux. The Archbishop replied that the Bishop had been captured in arms, and that the King thought it inexpedient to serve the citation on his prisoner, but would send envoys with explanations. On June 18, the Pope addressed a bull to the Archbishop of York and the Bishop of Carlisle directing them to excommunicate Bruce and his adherents, and to lay their lands, castles, and towns under ecclesiastical interdict till they should purge their offence. Already, on June 5, according to the London Annalist, the Archdeacons of Middlesex and Colchester had formally excommunicated Bruce and three other knights at St Paul's for the death of Comyn.
However the sacrilegious deed at Dumfries may have affected the attitude of Scotsmen generally to Bruce, it did not produce revulsion in the minds of the more ardent patriots, any more than in the minds of Bruce's personal friends. Yet not only the powerful Comyn interest, but also a very large section of the rest of the population, adhered, formally at least, to the English cause. The particular movements of Bruce are not on record; but it appears that his adherents were pressing Sir Alexander de Abernethy in Forfar Castle, and that Irish as well as Scots allies were active in Fife and Gowrie. The foresters of Selkirk, as we have seen, had stood by Edward, and apparently had suffered not a little for their fidelity. Hemingburgh says Bruce 'did great wonders': undoubtedly the impression is that he must have been fighting a strenuous uphill battle. The great mass of the nation, however, was waiting for more definite developments.
In June, Sir Aymer de Valence had advanced from Berwick to Perth. In his company were several prominent Scots—Sir John de Mowbray, Sir Ingram de Umfraville, Sir Alexander de Abernethy, Sir Adam de Gordon, Sir David de Brechin, and others that leant to Comyn. He had received to the peace some complaisant Scots whose lands or dwellings lay on his northward route. Bruce probably kept him under observation, retiring before him beyond the Forth, and not attempting to bar his progress to Perth.
On June 25, Bruce, no doubt reinforced, appeared before the walls of Perth, and challenged Sir Aymer to come out and fight him, or else to surrender. Hemingburgh assigns to Valence only 300 men-at-arms and some foot, a smaller force, he says, than Bruce had; but it is most unlikely that Valence was not the stronger, though possibly not by 1500 men, as Barbour alleges. Valence seems to have been ready to accept Bruce's challenge, but to have been dissuaded by his Scots friends. Umfraville, says Barbour, advised him to promise battle on the morrow, but to attack that night when the Scots were off guard in reliance on his promise. Bruce—'too credulous,' says Hemingburgh—accepted the promise. He was not in a position to establish a siege, and he retired to Methven Wood. His main body set about preparing food, and disposed themselves at ease, while parties went out to forage. In the dusk of the evening, Valence issued from Perth and took Bruce by surprise. It is not to be supposed, as the chroniclers narrate, that Bruce was so inexperienced as to allow his men to lie in careless unreadiness: no doubt many of them would have laid aside their arms; but the very fact that his knights at least fought with loose linen tunics over their armour to hide their distinctive arms would seem to show that they at any rate were prepared. Still they did not expect attack. They promptly rallied, however, and met with vigour the sudden and furious onset. Bruce, keenly realising the importance of the issue, bore himself with splendid valour. Before his fierce charge, the enemy gave way; and, Langtoft says, he killed Valence's charger. Thrice was he unhorsed himself, and thrice remounted by Sir Simon Fraser. According to Sir Thomas Gray, he was taken prisoner by John de Haliburton, who let him go the moment he recognised him. Barbour tells how he was hard beset by Sir Philip de Mowbray, and was rescued by Sir Christopher de Seton. But the day was going against him, and it was in vain that he made a supreme effort to rally his men. He was compelled to retreat. Barbour asserts that the English were too wearied to pursue, and retired within the walls of Perth with their prisoners, keeping there in fear of the approach of Bruce; but it seems far more likely, as Langtoft relates, that they kept up the pursuit 'for many hours.' The statement of Hemingburgh and others that the English pursued Bruce to Cantyre, and besieged and took a castle there, mistakenly supposing him to be in it, is evidently a misconception, and a confusion of Dunaverty with Kildrummy.
Bruce lost comparatively few men in the battle—the 7000 of the Meaux chronicle need not be considered—but a number of his ablest supporters were taken prisoners, notably Thomas Randolph, his nephew, Sir Alexander Fraser, Sir David Barclay, Sir Hugh de la Haye, Sir David de Inchmartin, and Sir John de Somerville. The Bishop of St Andrews had surrendered to Valence before the battle, but had taken care to send his household to fight for Bruce. His calculation is said to have been 'that if the Scots beat the English they would rescue him as a man taken by force for lack of protection, whereas, if the English won the day, they would mercifully regard him as having been abandoned by his household, as not consenting to their acts.' But this looks like a speculation of the chronicler's. Valence displayed humane consideration for his prisoners, all the more honourable as he had not yet received Edward's letter of June 28, modifying his previous bloodthirsty orders.
After the defeat, Bruce's party broke up into several groups. Sir Simon Fraser was captured at Kirkincliffe, near Stirling. Sir Christopher de Seton was taken at Lochore Castle in Fife. The Earl of Lennox made for his own fastnesses. Bruce himself proceeded northwards to Aberdeen. Barbour says he had about 500 followers, the most prominent of whom were his brother Sir Edward, the Earls of Athol and Errol, Sir William Barondoun, James of Douglas, and Sir Nigel Campbell. He kept to the high ground, not venturing to the plains, for the population had outwardly passed to the English peace again. Barbour tells pitifully how the fugitives' clothes and shoon were riven and rent before they reached Aberdeen. Here they were met by Nigel Bruce, the Queen, and other ladies; and here Bruce rested his company 'a good while.'