On 6 Aug. 1307 Gaveston received a grant of the earldom of Cornwall and of all lands late belonging to Edmund, late earl of Cornwall, the son of the king of the Romans; and on 29 Oct. following he was betrothed to Margaret de Clare, sister of the young Earl of Gloucester, and the king's own niece, and obtained with her large possessions in various parts of the kingdom. In his promotion to the earldom he had the support of the Earl of Lincoln, and by his marriage he became allied to a powerful house. But his pride could not be satisfied, and, as an instance of his personal vanity, one of the chroniclers notices that by royal command persons were forbidden to address him otherwise than by his title, an unusual practice at that period (ib. ii. 157). On 2 Dec. he held a tournament at Wallingford, in honour of the king's approaching marriage, but only increased his unpopularity with the barons, and particularly with the Earls of Warenne, Hereford, and Arundel, by defeating them in the lists.
On 30 Dec. Gaveston was appointed regent of the kingdom during Edward's absence in France on his marriage, although the king did not actually depart till 22 Jan. 1308, and was absent till 7 Feb. On 25 Feb. was celebrated the coronation, which had originally been appointed to take place a week earlier, and is even said to have been deferred on account of the growing discontent against the royal favourite. Here Gaveston's display eclipsed his rivals, and it is noticed as a special affront to the other nobles that he was appointed to carry in the procession the crown of St. Edward. His other services were the redemption of the ‘curtana’ sword, and the fixing of the spur on the king's left foot. His ostentation and the king's obtrusive partiality for him are also said to have disgusted the queen's relatives who were present, and who, on their return home, imparted their prejudice to the king of France. Seeing the storm rising, Edward postponed the meeting of the council, but at length, on 28 April, the barons assembled, and at once proceeded to call for Gaveston's banishment. Hugh Despenser (1262–1326) [q. v.] is said to have been the only man of importance who attempted to defend him. The king was forced to comply, and on 18 May issued his letters patent which proclaimed the sentence, the prelates undertaking to excommunicate Gaveston if he disobeyed; but, to soften the blow, Edward heaped fresh gifts upon him, and on 16 June appointed him lieutenant of Ireland, and at the same time prayed the pope to intervene for his protection. Gaveston sailed for his new command on 28 June from the port of Bristol, whither he was accompanied by the king in person, and remained in Ireland for a year. He established himself as Edward's representative at Dublin, and reduced the hostile septs in the neighbourhood, restored the fortresses, and carried out other works. But the king could not exist without his friend. Before many months had passed he was working for his recall; in April 1309 he tried to move the king of France to intercede in his favour, and, although parliament refused to sanction the favourite's return, he at length prevailed upon the pope to absolve him. Early in July Gaveston was welcomed by the king at Chester.
At an assembly of the barons at Stamford on 27 July, the king accepted the articles of redress previously presented to him by the parliament, and, though the mediation of the Earl of Gloucester, the Earls of Lincoln and Warenne were drawn over to Gaveston's side, and a large number of the barons gave their formal assent to his return. But Gaveston's insolence only increased, and he appears to have chosen this inopportune moment for forcing upon the earls opprobrious nicknames in ridicule of their personal peculiarities or defects. The Earl of Lincoln was ‘burst-belly’ (boele crevée); Lancaster was ‘the fiddler’ (vielers), or ‘play-actor’ (histrio); Gloucester, his own brother-in-law, was ‘horeson’ (filz à puteyne); and Warwick was ‘the black hound of Ardern.’ ‘Let him call me hound,’ exclaimed the latter; ‘one day the hound will bite him’ (Chron. Lanercost, p. 216). He is specially accused at this period of appropriating the revenues of the kingdom to such an extent that the king was straitened for means to support the charges of his court, and the queen was subjected to unworthy reductions, of which she bitterly complained to her father.
Within three months of his return Gaveston had again estranged those to whom he had but just now been reconciled. A council was summoned at York in October, but Lancaster and others refused to appear. Fearful for his safety, Edward kept Gaveston close to his side, and they passed the Christmas of 1309 together at Langley. In February 1310 the bishops and barons were again summoned, and when they met in March the barons attended in arms. Edward was compelled to submit to the election of a commission of ordainers invested with power to frame ordinances for the reform of the government. In February Gaveston had withdrawn from court. In September the king marched against the Scots, and was joined by Gaveston at Berwick, where they remained until the end of July of the next year (1311). But then Edward was obliged to return to London to meet