, showing how Harclay's forces cut off Lancaster's passage across the river. Harclay's most prominent achievement came with the
Battle of Boroughbridge in 1322. The battle was the culmination of an ongoing struggle between King
Edward II and his most powerful earl,
Thomas of Lancaster. The conflict stemmed from disagreement over the handling of the war with Scotland; Lancaster, and many others, found the king's war effort lacking. After failing to incite an insurrection against the king, Lancaster was in March 1322 fleeing northwards from the royal army. Meanwhile, Harclay, as sheriff of Cumberland, was ordered by the king to levy the forces of the northern counties of
Cumberland and
Westmorland, and move south. His orders were to meet up with the royal army, but while stopping at the town of
Ripon in Yorkshire, he received intelligence that Lancaster would arrive at nearby
Boroughbridge the next day. Harclay decided to take the initiative, and occupy the bridge that would prevent Lancaster's passage across the
River Ure. Lancaster's army arrived at Boroughbridge on 16 March. The rebels were greatly outnumbered; while Harclay commanded around 4000 men, Lancaster only had some 700
knights and
men-at-arms, with followers, in his service. In addition to this, the loyalist forces were highly trained and experienced from the Scottish Wars. Harclay used tactics the English had learned from the Scots in these wars. According to
The Brut, Lancaster tried to persuade Harclay to join his side, in return for great rewards in land. Harclay had previously been a supporter of Lancaster, possibly also the earl's
retainer; in 1318, a general royal pardon for Lancaster and his adherents contained Harclay's name. Lancaster's plan was to charge across a ford in the river, while the
Earl of Hereford – one of the few
magnates who had remained loyal to Lancaster – crossed the bridge. Hereford was killed on the bridge, his companion
Roger de Clifford, 2nd Baron de Clifford was badly wounded, and this advance failed. Lancaster, meanwhile, came under such heavy archery fire that he had to call off his attack. Defections during the night, combined with royal reinforcements, forced him to surrender the next day, and on 22 March he was executed. The king was greatly pleased with Harclay's effort, and rewarded him lavishly. On 25 March, Harclay was created
Earl of Carlisle, and given land worth 1000
marks a year. On 15 September, he was also made chief
Warden of the Marches. ==Treason==