On Henry's death in 1135, Stephen rushed to England. Ignoring the claim of his elder brother, Theobald, already Count of Blois, he entered London and declared himself king. The barons preferred him to Matilda and so ratified the usurpation, the main opposition coming from Matilda's illegitimate half-brother, Robert of Gloucester, who never supported Stephen whole-heartedly. The Archbishop of Canterbury and Pope Innocent II sided with Stephen. Matilda's best hope, her uncle, King David I of Scotland, invaded Northumberland, nominally on her behalf. Little actual fighting took place, but Stephen won the Battle of the Standard in August 1138.
Later in the same year, Robert of Gloucester changed sides and allied himself with Geoffrey of Anjou. Stephen, meanwhile, made a series of poor decisions that caused resentment amongst his former supporters. His own brother, Henry, Bishop of Winchester, turned against him, and in 1139 Matilda entered England and made a stand at Arundel Castle. Stephen unwisely allowed her to travel to Bristol to meet up with Robert of Gloucester, and they had soon amassed enough support to march on Lincoln. In the only major battle of the struggle, Stephen suffered defeat on February 2, 1141. He was made a prisoner at Bristol, and Matilda temporarily ruled from London. However, her haughty manner soon made her enemies there, and she felt obliged to leave the capital for Oxford. In September of 1141, Robert of Gloucester fell into enemy hands, and Matilda decided to get him back via an exchange for Stephen, who returned to the throne. He now held most of the country and besieged Matilda at Oxford Castle. Her escape by night in the snow has become legendary.
Unrest continued throughout Stephen's reign, even after Matilda had returned to Anjou following Robert's death in 1147. The period saw increasing lawlessness and weak government: as the saying has it: "Christ and all his saints slept". For this reason the popular name "The Anarchy" arose.
Stephen himself kept poor health by this time, and he suffered a further blow when his eldest son, Eustace, died suddenly in 1153 -- Stephen had wanted Eustace crowned during his own lifetime, but the Pope had refused to allow it and even put England under an interdict for a time during the squabble. Matilda's son, the future Henry II of England, had by now grown up into a skilled military tactician and a determined opponent, and he arrived in England with the intention of conquest. By the Treaty of Wallingford, which the two men signed in November 1153, Stephen recognised Henry as heir to the throne. Rumours already circulating for years that Stephen was Henry II's biological father were reinforced by his agreement to let Henry succeed him although he had another surviving son (William, Count of Boulogne (d. 1160)), but no evidence supporting that story has ever emerged. Matilda never ruled in her own right.
Although not traditionally a popular period with historical novelists, the Anarchy has furnished the background of two major fictional portrayals in recent years. Ellis Peters set her series of Brother Cadfael books (published 1977 - 1994) against the background of the Anarchy. Sharon Kay Penman's 750-page novel, When Christ and His Saints Slept (published in 1995), gives a comprehensive and informative view of the entire power struggle.