King of England from 1135 to 1154, nephew of Henry I., his mother being Adela, daughter of William I.; acquired French possessions through the favour of his uncle and by his marriage; in 1127 swore fealty to his cousin Matilda, daughter of Henry I., as his future sovereign, but on the death of his uncle usurped the throne, an action leading to a violent civil war, which brought the country into a state of anarchy; the Scots invaded on behalf of Matilda, but were beaten back at Northallerton (the Battle of the Standard, 1138); foreign mercenaries introduced by the king only served to embitter the struggle; the clergy, despoiled by the king, turned against him, and in the absence of a strong central authority the barons oppressed the people and fought with one another; "Adulterine Castles" sprang up over the country, and "men said openly that Christ and His saints were asleep"; in 1141 Matilda won the battle of Lincoln and for a few months ruled the country, but "as much too harsh as Stephen was too lenient," she rapidly became unpopular, and Stephen was soon again in the ascendant; the successes of Henry, son of Matilda, led in 1153 to the treaty of Wallingford, by which it was arranged that Stephen should retain the crown for life, while Henry should be his heir; both joined in suppressing the turbulent barons and the "Adulterine Castles"; more fortunately circumstanced, Stephen had many qualities which might have made him a popular and successful king (1105-1154).