The greatness Eadward had thus secured descended to his son Æthelstan, with whom the grandeur of the Saxon monarchy reached its highest point. He married one of his sisters to a Northumbrian prince, Cytric, receiving his allegiance for Benicia from the Tees to Edinburgh, and, on the death of Cytric, incorporated the country with his own dominions. Cytric’s two sons fled, the one to Ireland, where the Danes received him willingly, the other (Guthrith) to Constantine, King of Scotland. The consequence of the escape of these princes became evident in after years. In 934, Constantine and his heir Eorca, Owen or Eugenius, King of Cumberland, made war upon England, but were defeated and compelled to acknowledge the supremacy of Æthelstan. The attention of the English King was subsequently drawn abroad, where he upheld the cause of his nephew, Louis de Outre-Mer, son of Charles the Simple, against the attacks of his brothers-in-law, the German Otto and Hugh of Paris. It was while thus employed that the Scotch kingdoms again rose in insurrection. A great conspiracy against Æthelstan appears to have been formed, at the head of which were Anlath, son of that Guthrith who had fled to Scotland, Constantine, Owen, and several princes of the Danes from Ireland. Their object was the re-establishment of the Danish power in Northumbria. The attempt was completely thwarted by the great battle of Brunanburh, near Beverley, in Yorkshire. Not long after this decisive victory Æthelstan died. His splendid reign is further marked by legislation of a more original description than that of his predecessors. He ordered, among other things, that every man should have a lord who should be answerable for him to justice, and rendered more systematic the arrangement of mutual responsibility, which appears to have been one of the principles of Saxon police. [Sidenote: Eadmund. 940-946.] [Sidenote: Eadred. 946-955.] His younger brothers, Eadmund and Eadred, followed in his footsteps, defeating the Northumbrian rebels, who from time to time elected kings of their own, but were completely conquered by Eadred. He so thoroughly incorporated the country with his own, that its ruler could no longer claim the title of king. Both Bernicia and Deira were bestowed as an earldom on Osulf, who had assisted in the conquest of the rebels, and remained in the hands of his family till the Norman Conquest. Eadmund also maintained his supremacy over Scotland, with which country his relations were of a very friendly nature, as he granted a part of the kingdom of Strathclyde, consisting of Cumberland and Galloway, to King Malcolm, to be held by military service. [Sidenote: Rise of Dunstan.]