The Anarchy was the first civil war in post-Conquest England, enduring throughout the reign of King Stephen between 1135 and 1154. It ultimately brought about the end of the Norman dynasty and the birth of the mighty Plantagenet kings. When Henry I died having lost his only legitimate son in a shipwreck, he had caused all of his barons to swear to recognize his daughter Matilda, widow of the Holy Roman Emperor, as his heir and remarried her to Geoffrey, Count of Anjou. When she was slow to move to England on her father's death, Henry's favourite nephew Stephen of Blois rushed to have himself crowned, much as Henry himself had done on the death of his brother William Rufus.

Supported by his brother Henry, Bishop of Winchester, Stephen made a promising start, but Matilda would not give up her birthright and tried to hold the English barons to their oaths. The result was more than a decade of civil war that saw England split apart. Empress Matilda is often remembered as aloof and high-handed, Stephen as ineffective and indecisive. By following both sides of the dispute and seeking to understand their actions and motivations, Matthew Lewis aims to reach a more rounded understanding of this crucial period of English history and asks to what extent there really was anarchy.