Warfare in Medieval Scotland and supply his armies. Part of the reason for Robert I's success was his ability to call on naval forces from the Islands. As a result of the expulsion of the Flemings from England in 1303, he gained the support of a major naval power in the North Sea. The development of naval power allowed Robert to successfully defeat English attempts to capture him in the Highlands and Islands and to blockade major English controlled fortresses at Perth and Stirling, the last forcing Edward II to attempt the relief that resulted at English defeat at Bannockburn in 1314. Scottish naval
Robert the Bruce at Ramsey in the Isle of Man, laid siege to Castle Rushen in Castletown, capturing it on 21 June 1313 and denying the English the island's strategic importance. The eight years of exhausting but deliberate refusal to meet the English on even ground have caused many to consider Bruce one of the great guerrilla leaders of any age. This represented a transformation for one raised as a feudal knight. By 1314, Bruce had recaptured most of the castles in Scotland held by the English and was sending raiding parties into northern England as far as Carlisle. In response, Edward II