In 1153, following the death of his son Eustace, Stephen eventually signed an agreement with the Empress Matilda to end the Anarchy. The Treaty of Wallingford, Winchester or Westminster (as it's variously known) allowed Stephen to keep the throne, but he agreed to recognise Matilda's son Henry as his heir over his surviving son, William of Boulogne. Stephen died in October 1154, less than a year after the signing of the treaty, and was duly succeeded by Matilda's son as King Henry II. Henry's father was Geoffrey of Anjou, nicknamed Plantagenet; Henry II would later come to be known as the first Plantagenet King of England, but he and his two sons were known in their day as the Angevin kings (belonging to the House of Anjou).
Stephen was the grandson of William I; his mother, Adela of Normandy, was William's ninth and last child (and fifth daughter). Matilda was also the Conqueror's grandchild (being the daughter of King Henry I) and so her son was William's great–grandson. This made him Stephen's first cousin, once removed (downwards).
© Haydn Thompson 2021