in the British Isles to be bombarded by cannon". In late June, the defenders set adrift burning brushwood soaked in tar, in an attempt to repel a naval assault. Instead of the English ships, much of the town was set on fire. William Seton, a son of the town's governor, was killed fighting an English seabourne assault. By the end of June the attacks by land and sea had brought the town to a state of ruin and the garrison close to exhaustion. It is believed that a desire for a respite from the plunging fire of the two large counterweight trebuchets used by the English was a significant factor in Seton requesting a short truce from King Edward. This was granted, but only on the condition that he surrender if not relieved by 11 July. Seton's son, Thomas, was to be a hostage to the agreement, along with eleven others. Relief force 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