The Anarchy England. An illegitimate son of Henry I and the half-brother of the Empress Matilda, Robert was one of the most powerful Anglo-Norman barons, controlling estates in Normandy as well as the Earldom of Gloucester. In 1138, Robert renounced his fealty to Stephen and declared his support for Matilda, triggering a major regional rebellion in Kent and across the south-west of England, although Robert himself remained in Normandy. Matilda had not been particularly active in asserting her claims to throne since 1135 and in many ways it was Robert that took the initiative in declaring war in 1138. In France, Geoffrey
Henry I of England now had the best claim to the throne. William of Breteuil championed the rights of Robert, who was still abroad, returning from the Crusade, and to whom Henry and the barons had given homage in previous years. Henry argued that, unlike Robert, he had been born to a reigning king and queen, thereby giving him a claim under the right of porphyrogeniture. Tempers flared, but Henry, supported by Henry de Beaumont and Robert of Meulan, held sway and persuaded the barons to follow him. He occupied Winchester Castle and seized the royal treasury. Henry was hastily crowned king in Westminster