The year after the marriage, Geoffrey's father, Fulk, left on
crusade for
Jerusalem (where he was to later become king), leaving Geoffrey behind as count of Anjou. When his father in law, King Henry I of England, died in 1135, Geoffrey supported Matilda in entering Normandy to claim her inheritance. The border districts submitted to her, but in England her first cousin
Stephen of Blois had been crowned king, supported by a number of barons after claims that Henry I had changed his mind on his deathbed in regard to his heir. Barons in Normandy soon followed suit, or were in a large majority the same barons as in England. There were a number that supported Matilda, her claim to the throne, and the two vows that they had taken at the request of Henry, for her to be his heir. The following year, Geoffrey gave Ambrieres, Gorron, and Chatilon-sur-Colmont to Juhel de Mayenne, on condition that he help obtain the inheritance of Geoffrey's wife. In 1139, Matilda landed in England with 140 knights, where she was besieged at
Arundel Castle by King Stephen. In
the Anarchy which ensued, Stephen was captured at Lincoln in February 1141, and imprisoned at Bristol. A legatine council of the English church held at Winchester in April 1141 declared Stephen deposed and proclaimed Matilda "Lady of the English". Geoffrey held the duchy until 1149, when he and Matilda conjointly ceded it to their son, Henry, which cession was formally ratified by King
Louis VII of France the following year. Geoffrey also put down three baronial rebellions in Anjou, in 1129, 1135 and 1145–1151. He was often at odds with his younger brother,
Elias, whom he had imprisoned (until Elias died in 1151). The threat of rebellion slowed his progress in Normandy, and is one reason he could never assist in England. Geoffrey died later the same year, aged 38, and Henry took his father's place as head of the ducal house. In 1153, the
Treaty of Wallingford stipulated that Stephen should remain King of England for life and that Henry, the son of Geoffrey and Matilda should succeed him, beginning the Plantagenet era in English history. ==Death==