Kingdom of Scotland 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 in English defeat at Bannockburn in 1314. Scottish naval forces allowed invasions of the Isle of Man in 1313 and 1317 and Ireland in 1315. They were also crucial in the blockade of Berwick, which led to its fall in 1318. After the establishment of Scottish independence, Robert
Robert the Bruce eventually lifted Bruce's excommunication. In May 1328 King Edward III of England signed the Treaty of Edinburgh-Northampton, which recognised Scotland as an independent kingdom, and Bruce as its king. In 1325 Robert I exchanged lands at Cardross for those of Old Montrose in Angus with Sir David Graham. It was to be here that Robert would build the manor house that would serve as his favoured residence during the final years of his reign. The extant chamberlain's accounts for 1328 detail a manor house at Cardross with king's and queen's chambers and glazed windows, a chapel, kitchens, bake- and brew-houses,