Following the death of Henry I of England in 1135, a war, known in Britain as the Anarchy or the 19 Years Winter broke out between rival contenders Stephen of Blois, the king's nephew, and Matilda, wife of the Count of Anjou, the kings daughter. From across the Channel, however, the jealous eyes of Robert, brother of the late Henry and Duke of Normandy, watched the proceedings with interest. Being the oldest son of William I of England, he believed that, by right of primogeniture, he was entitled also to the throne of England. Therefore, a year after his brother's death, Robert laid claim to the English throne.