Stirling Castle castle, if it were not relieved by 24 June 1314. Bruce agreed, and withdrew. The following summer, the English duly headed north, led by Edward II, to save the castle. On 23–24 June, King Robert's forces met the English at the Battle of Bannockburn, within sight of the castle walls. The resulting English defeat was decisive. King Edward attempted to take refuge in the castle, but Mowbray was determined to keep to his word, and the English were forced to flee. Mowbray handed over the castle, changing sides himself in the process. King Robert ordered the castle to be slighted;
Robert the Bruce planned a major military campaign with the support of Lancaster and the barons, mustering a large army of between 15,000 and 20,000 men. In the spring of 1314, Edward Bruce laid siege to Stirling Castle, a key fortification in Scotland whose governor, Philip de Mowbray, agreed to capitulate if not relieved before 24 June 1314. In March, James Douglas captured Roxburgh, and Randolph captured Edinburgh Castle, while in May, Bruce again raided England and subdued the Isle of Man. News of the agreement regarding Stirling Castle reached the English king in late May, and he decided to speed his march