Military history of Scotland 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 forces allowed invasions of the Isle of Man
Robert the Bruce a period with one or more allied English noble families, such as the de Clares of Gloucester, or perhaps even in the English royal household. Sir Thomas Grey asserted in his "Scalacronica" that in about 1292, Robert the Bruce, then aged eighteen, was a 'young bachelor of King Edward's Chamber'. While there remains little firm evidence of Robert's presence at Edward's court, on 8 April 1296 both Robert and his father were pursued through the English Chancery for their private household debts of £60 by several merchants of Winchester. This raises the possibility that young Robert the Bruce was on