Battle of Wilton Boulogne to England and claimed the throne. He quickly gained the support of London's magnates and the church, and seized control of the treasury at Winchester. He was crowned king on 22 December 1135. By 1138, Matilda had gathered enough support to challenge Stephen for the throne. Her supporters were led by her half-brother Robert Earl of Gloucester. The ensuing civil war lasted until 6 November 1153 when, by the Treaty of Wallingford, Stephen recognised Matilda's son Henry as heir to the throne. By 1142 both sides had become cautious of risking open battle, and the civil war became a
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