The death of Henry I in 1135 brought an end to the amicable relations between the kings of England and Scotland, and radically altered the balance of power in the border regions. Until then Robert de Brus had been able to pay fealty to the king of Scots for Annandale without compromising his position as a major tenant-in-chief of the English king in Cleveland and Hartness. The accession of Stephen de Blois was to place that dual allegiance under severe strain. In company with the majority of magnates and barons who had prospered as King Henry's ‘new men’, Robert had little hesitation in accepting Stephen as king. He was with Stephen in York during his tour of the North soon after his coronation, and again at the siege of Exeter in the summer of 1136. King David on the other hand seized the opportunity he may well have been waiting for, when Henry's firm hold had been removed, to renew his claim to the northern counties of England with an armed invasion, ostensibly in the name of his niece. So in August 1138, when the Scottish and English armies were preparing to confront one another on Cowton Moor near North-allerton, Robert de Brus had at last to choose between his two allegiances. He was not the only one. Bernard de Balliol, who had sworn a personal oath of loyalty to David, renounced it; Eustace fitz John, who had been Henry's justice in the North and lord of Alnwick, chose to support the Scots.