Before David I became the King of Scotland in 1124, he was the prince of the Cumbrians and earl of a great territory in the middle of England acquired by marriage. This period marks the beginning of his life as a great territorial lord. Circa 1113, the year in which King Henry I of England arranged his marriage to an English heiress and the year in which for the first time David can be found in possession of "Scottish" territory, marks the beginning of his rise to Scottish leadership. Introduction — David and Henry I No historian is likely to deny that David I's early career was largely manufactured for him by King Henry I of England. David was one of Henry's "new men", and his "greatest protégé"; Henry's influence had brought David his English marriage and lands, and Henry's military power had allowed David to take up his Scottish lands. David's early career can be understood as part of Henry's frontier policy, which included marriage of two daughters to the kings of Scotland and Galloway, consolidation of royal control in the north-west coast of England and the quelling of the Montgomeries, marcher lords on the Welsh borders who had been allied to Muirchertach Ua Briain, High King of Ireland (1101–19). The world of peace which David had enjoyed in England ended after the death of Henry I, just as it did for most other English magnates. When Henry I first became king of England, he did so in circumstances that were very irregular. William II, it was said, had been killed in a hunting accident in the New Forest. Henry tentatively assumed power while his elder brother Robert, duke of Normandy and the rightful heir, was on crusade. Thus, as a usurper within his own dynasty, he cast about for a claim to legitimacy. He found it in a marriage to David's sister Edith, often called Matilda in Norman fashion, who had accompanied David in his exile. She was a descendant of the near-extinct dynasty of Wessex through her mother, and thereby provided a crude but effective means to create a legal basis for his rule. As an added benefit, from Henry's viewpoint, she might also provide some protection against further Scottish incursions like those that had plagued the northern English provinces with regularity under Malcolm III. This is not to argue that Henry I and David could not