Fulk FitzWarin at the time of his death in 1197. Whittington Castle lies on the English side of Offa's Dyke, which during the Norman era and before was the border between England and Wales. The site was fortified as a castle by William Peverel in 1138, in support of Empress Matilda, the daughter of King Henry I (1100–1135), in her struggle (known as The Anarchy) for the throne against King Stephen (1135–1154), grandson of William the Conqueror. In the late 1140s the lordship of Whittington, like Oswestry and Overton ceased to be part of England and became part of the Kingdom of
Sussex in the High Middle Ages England was unsuccessful. Following charges against Robert de Bellême around his support for the failed invasion of Robert Curthose, Robert de Bellême fortified Arundel Castle around 1101. This led to forces of Henry I besieging Arundel Castle in 1102 for 3 months, building siege castles in the vicinity of Arundel including probably at Warningcamp and perhaps Ford. Henry I's forces confiscated the castle and held it himself. As the second wife of Henry I Adeliza of Louvain was Queen of England from 1121 until Henry's death in 1135. On their marriage in 1121 Henry gave Adeliza the city of Chichester