In 1125 Stephen swore fidelity to Henry's daughter Matilda, to succeed her father to the throne. Upon Henry's death, however, Stephen proclaimed himself king. He was opposed by many English barons and by Matilda and her supporters, and his reign was troubled by anarchy and constant internal wars.
For six months in 1141 he was Matilda's prisoner, during which time she reigned as queen. Stephen was restored to the throne, but for five years Matilda and many of the nobles continued to oppose him. During the course of the frequent civil wars, much of the land was ravaged, and England was plunged into almost complete chaos.
In 1148 Matilda left England and gave up her claim in favor of her son, Henry of Anjou, later Henry II. Henry then waged war against Stephen until 1153, when Stephen was forced to name Henry his heir.