Pending this negotiation, the Earl of Angus, at that time one of the most powerful of the Scottish nobles, having, by the promise of an English dukedom from the exiled Henry, engaged to assist in restoring him to his crown and dominions, the Earl of Ross, before the plan had been organized, in order to counteract the attempt, broke out into open rebellion, which was characterized by all those circumstances of barbarous cruelty which distinguished the inroads of the princes of the islands. He first seized the castle of Inverness at the head of a small party, being admitted unawares by the governor, who did not suspect his hostile intentions. He then collected a considerable army, and proclaimed himself king of the Hebrides. With his army he entered the country of Athole, denounced the authority of the king, and commanded all taxes to be paid to him; and, after committing the most dreadful excesses, he stormed the castle of Blair, dragged the Earl and Countess of Athole from the chapel of St. Bridget, and carried them off to Isla as prisoners. It is related that the Earl of Ross thrice attempted to set fire to the holy pile, but in vain. He lost many of his war-galleys, in a storm of thunder and lightning, in which the rich booty he had taken was consigned to the deep. Preparations were immediately made by the regents of the kingdom for punishing this rebellious chief; but these became unnecessary, for, touched with remorse, he collected the remains of his plunder, and stripped to his shirt and drawers, and barefooted, he, along with his principal followers, in the same forlorn and dejected condition, went to the chapel of St. Bridget which they had lately desecrated, and there performed a penance before the altar. The Earl and Countess of Athole were thereupon voluntarily released from confinement, and the Earl of Ross was afterwards assassinated in the castle of Inverness, by an Irish harper who bore him a grudge.[159] Although at this period an account of Orkney and Shetland does not properly belong to a history of the Highlands, as these islands had for long been the property of the king of Norway, and had a population almost purely Teutonic, with a language, manners, and customs widely differing from those of the Highlanders proper; still it will not be out of place to mention here, that these islands were finally made over to Scotland in 1469, as security for the dowry of Margaret of Norway, the wife of James III.