The forces of King Edward I of England invaded Scotland at the start of the war, and seized Bothwell, also capturing Walter's son, William Moray of Bothwell. The English garrison holding the castle was besieged by the Scots for 14 months in 1298—1299, and eventually capitulated. Edward I returned in 1301, capturing the castle once more with a force of 6800 men, and specially constructed siege engines. Bothwell became the headquarters of Aymer de Valence, 2nd Earl of Pembroke, Edward's appointed Warden of Scotland, and remained in English hands for several years.