Douglas was now faced with a situation similar to that which the English had faced before the
Battle of Bannockburn. Nicholson considers that "If Berwick were to be saved immediate action on the part of the Scottish guardian was unavoidable". As a matter of national pride Douglas would have to come to the relief of Berwick, just as Edward II had come to the relief of
Stirling Castle in 1314. The army that Douglas had spent so much time gathering was now compelled to take to the field. The English army is estimated to have been less than 10,000 strong – outnumbered approximately two-to-one by the Scots. Douglas entered England on 11July, the last day of Seton's truce. He advanced eastwards to Tweedmouth and destroyed it in sight of the English army. Edward III did not move.
Sir William Keith, with Sir Alexander Gray and
Sir William Prenderguest, led a force of around 200 Scottish cavalry. With some difficulty, they forced their way across the ruins of the bridge to the northern bank of the Tweed and made their way into the town. Douglas considered the town relieved. He sent messages to Edward III calling on him to depart, threatening that if he failed to do so, the Scots army would devastate England. The Scots were challenged to do their worst. The defenders argued that Keith's 200 horsemen constituted the relief according to the truce and therefore they did not have to surrender. Edward III stated that this was not the case: they had to be relieved directly from Scotlandliterally from the direction of Scotlandwhereas Keith, Gray and Prenderguest had approached Berwick from the direction of England. Edward III ruled that the truce agreement had been breached – the town having neither surrendered nor been relieved. A gallows was constructed directly outside the town walls and, as the highest-ranking hostage, Thomas Seton was hanged while his parents watched. Edward III issued instructions that each day the town failed to surrender, another two hostages should be hanged. Keith, having taken command of the town from Seton, concluded a fresh truce on 15 July, promising to surrender if not relieved by sunset on 19July. The truce comprised two
indentures, one between Edward III and the town of Berwick and the other between Edward III and March, the keeper of Berwick Castle. It defined circumstances in which relief would or would not occur. The terms of surrender were not
unconditional. The town was to be returned to English soil and law but the inhabitants were to be allowed to leave, with their goods and chattels, under a
safe conduct from Edward III. All members of the garrison would also be given free passage. Relief was defined as one of three events: 200 Scottish men-at-arms fighting their way into Berwick; the Scottish army forcing its way across a specific stretch of the River Tweed; or, defeat of the English army in open battle on Scottish soil. On concluding the new treaty, Keith was allowed to immediately leave Berwick, travel to wherever the Guardian of Scotland happened to be, advise him of the terms of the treaty, and return safely to Berwick. By this time Douglas had marched south to Bamburgh, where Edward III's queen Philippa was still staying, and besieged it; Douglas hoped that this would cause Edward III to break off his siege. In 1319 Edward III's father, Edward II, had broken off a siege of Berwick after a Scottish army had advanced on York, where his queen was staying, and devastated Yorkshire. However, whatever concerns Edward III had for his queen, he ignored the threat to Bamburgh. The Scots did not have the time to construct the kind of equipment that would be necessary to take the fortress by assault. The Scots devastated the countryside but Edward III ignored this. He positioned the English army on
Halidon Hill, a small rise of some , to the north-west of Berwick, which gives an excellent view of the town and the vicinity. From this vantage point, he dominated the crossing of the Tweed specified in the indentures and would have been able to attack the flank of any force of men-at-arms attempting to enter Berwick. Receiving Keith's news, Douglas felt that his only option was to engage the English in battle. Crossing the Tweed to the west of the English position, the Scottish army reached the town of
Duns, from Berwick, on 18July. On the following day it approached Halidon Hill from the north-west, ready to give battle on ground chosen by Edward III. Edward III had to face the Scottish army to the front and guard his rear against the risk of a sortie by the garrison of Berwick. By some accounts, a large proportion of the English army was left guarding Berwick. To engage the English, the Scots had to advance downhill, cross a large area of marshy ground and then climb the northern slope of Halidon Hill. The Battle of Dupplin Moor the previous year had shown how vulnerable the Scots were to arrows. The prudent course of action would have been to withdraw and wait for a better opportunity to fight, but this would guarantee the loss of Berwick. The armies encountered each other's scouts around midday on 19July. Douglas
ordered an attack. The
Lanercost Chronicle reports: The Scots suffered many casualties and the lower reaches of the hill were littered with dead and wounded. The survivors continued upwards, through the arrows "as thick as motes in a sun beam", according to an unnamed contemporary quoted by Nicholson, and on to the waiting spears. The Scottish army broke, the camp followers made off with the horses and the fugitives were pursued by the mounted English knights. The Scottish casualties numbered in thousands, including Douglas and five earls dead on the field. Scots who surrendered were killed on Edward's orders and some drowned as they fled into the sea. English casualties were reported as fourteen; some chronicles give a lower figure of seven. About a hundred Scots who had been taken prisoner were beheaded the next morning, 20July. This was the date that Berwick's second truce expired, and the town and the castle surrendered on the terms in the indentures. ==Aftermath==