Previous king: John (father) Reigned: 1216-1272 Next king: Edward I (son)Henry III was only nine years old when he became king. His regents ruled England according to the rules in Magna Carter. However, when Henry grew up, he became more autocratic. Some of his barons resented this. They were led by Simon de Montfort. They forced him to sign the Provisions of Oxford in 1258, which led to the first English Parliament. There was civil war between Henry and Simon de Montfort. At the Battle of Lewes, 1264, Henry was defeated and taken prisoner. His son Edward (later Edward I) escaped, and Simon de Montfort was killed at the Battle of Evesham in 1265.