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
Henry I of France William until the former's death in 1060. In 1051, William married Matilda, the daughter of the count of Flanders, which Henry saw as a threat to his throne. In 1054, and again in 1057, Henry invaded Normandy, but on both occasions he was defeated. Henry had three meetings with Henry III, Holy Roman Emperor—all at Ivois. In early 1043, he met him to discuss the marriage of the emperor with Agnes of Poitou, the daughter of Henry's vassal. In October 1048, the two Henries met again and signed a treaty of friendship. The final meeting took place in May 1056