Henry II became King of England in 1154 after years of civil war, and through his marriage to Eleanor of Aquitaine expanded his territories across western France and Scotland, creating an Angevin Empire. He appointed his friend Thomas Becket as Archbishop of Canterbury to exert royal control over the church, but Becket resisted Henry's demands and was exiled for four years. After Becket's return, four knights loyal to Henry murdered Becket in Canterbury Cathedral in 1170, making him a martyr. Henry did penance at Becket's tomb and spent his later years struggling to maintain control over his rebellious sons.