result of which Jewish communities were often found close to castles. The Jews used the Tower as a retreat, when threatened by anti-Jewish violence. The death in 1135 of Henry I left England with a disputed succession; although the king had persuaded his most powerful barons to swear support for the Empress Matilda, just a few days after Henry's death Stephen of Blois arrived from France to lay claim to the throne. The importance of the city and its Tower is marked by the speed at which he secured London. The castle, which had not been used as a royal residence for some time, was usually left in the charge of a Constable, a post held at this time by Geoffrey de Mandeville. As the Tower was considered an impregnable fortress in a strategically important position, possession was highly valued. Mandeville exploited this, selling his allegiance to Matilda after Stephen was captured in 1141 at the Battle of Lincoln. Once her support waned, the following year he resold his loyalty to Stephen. Through his role as Constable of the Tower, Mandeville became "the richest and most powerful man in England". When he tried the same ploy again, this time holding secret talks with Matilda, Stephen had him arrested, forced him to cede control of his castles, and replaced him with one of his most loyal supporters. Until then the position had been hereditary, originally held by Geoffrey de Mandeville, but the position's authority was such that from then on it remained in the hands of an appointee of the monarch. The position was usually given to someone of great importance, who might not always be at the castle due to other duties. Although the Constable was still responsible for maintaining the castle and its garrison, from an early stage he had a subordinate to help with this duty: the Lieutenant of the Tower. Constables also had civic duties relating to the city. Usually they were given control of the city and were responsible for levying taxes, enforcing the law and maintaining order. The creation in 1191 of the position of Lord Mayor of London removed many of the Constable's civic powers, and at times led to friction between the two. Expansion The castle probably retained its form as established by 1100 until the reign of Richard I (1189–1199). The castle was extended under William Longchamp, King Richard's Lord Chancellor and