Viking raids and settlement in the ninth century, the Anglo-Saxon kingdom of Wessex emerged as the dominant English kingdom. Alfred the Great secured Wessex, achieved dominance over western Mercia, and assumed the title "King of the Anglo-Saxons". His grandson Æthelstan was the first king to rule over a unitary kingdom roughly corresponding to the present borders of England, though its constituent parts retained strong regional identities. The 11th century saw England become more stable, despite a number of wars with the Danes, which resulted in a Danish monarchy for one generation. The conquest of England in 1066 by William, Duke of Normandy, was crucial in terms of both political and social change. The new monarch continued the centralization of power begun in the Anglo-Saxon period, while the feudal system continued to develop. William was succeeded by two of his sons: William II, then Henry I. Henry made a controversial decision to name his daughter Matilda (his only surviving child) as his heir. Following Henry's death in 1135, one of William I's grandsons, Stephen, laid claim to the throne and took power with the support of most of the barons. Matilda challenged his reign; as a result, England descended into a period of disorder known as the Anarchy. Stephen maintained a precarious hold on power, but agreed to a compromise under which Matilda's son Henry would succeed him. Henry accordingly became the first Angevin king of England and the first monarch of the Plantagenet dynasty as Henry II in 1154. The reigns of most of the Angevin monarchs were marred by civil strife and conflicts between the monarch and the nobility. Henry II faced rebellions from his own sons, including the future monarchs Richard I and John, but nevertheless managed to expand his kingdom, forming what is retrospectively known as the Angevin Empire. Upon Henry's death, his eldest surviving legitimate son Richard succeeded to the throne; Richard was absent from England for most of his reign, for he left to fight in the Crusades. He was killed whilst besieging a castle; John succeeded him. John's reign was marked by conflict with the barons, particularly over the limits of royal power. In 1215, the barons coerced the king into issuing Magna Carta (Latin for "Great Charter") to guarantee the rights and liberties of the nobility. Soon afterwards, further disagreements plunged England into a civil war known as the First Barons' War. The