Harold knew how to make the authority of the King of England over his smaller neighbours respected. It was during his tenure of power that Siward, earl of Northumbria, was sent into Scotland to put down Macbeth, the lord of Moray, who had murdered King Duncan and seized his crown. Siward slew Macbeth in battle at Lumphanan, and restored to the throne of Scotland Malcolm, the eldest son of the late king (1054). A little later Harold himself took the field to put down Gruffyd, the King of North Wales, who had risen in rebellion. He drove the Welsh up into the crags of Snowdon, and besieged them there till they slew their own king and laid his head at the earl's feet. [Sidenote: =Harold's detention in Normandy.=] It was somewhere about this time that a misfortune fell upon Harold. He was sailing in the Channel, when a storm arose and drove his ship ashore on the coast of Ponthieu, near the Somme-mouth. Wido, the Count of Ponthieu, an unscrupulous and avaricious man, threw the earl into prison, and held him to ransom. But William, Duke of Normandy, who was Wido's feudal superior, delivered him from bonds, and brought him to his court at Rouen. Harold abode with the duke for some time, half as guest, half as hostage, for William would not let him depart. He went on an expedition against Brittany with the Normans, and received knighthood at the duke's hands. After a time he was told that he might return home if he would engage to use all his endeavours to get William elected King of England at the death of Edward. The duke said that he had gained such a promise from Edward himself, and thought he could make sure of the prize with Harold's aid. Thus tempted, the earl consented to swear this unwise and unjust oath, and in presence of the whole Norman court vowed to aid William's candidature. When he had sworn, the duke showed him that the shrine at which he had pledged his faith was full of the bones of all the saints of Normandy, which had been secretly collected to make the oath more solemn. [Sidenote: =Dissensions in England.--Eadwine and Morcar.=]