The Norman invasion of England in 1066 led to the defeat and replacement of the Anglo-Saxon elite with Norman and French nobles and their supporters. William the Conqueror and his successors took over the existing state system, repressing local revolts and controlling the population through a network of castles. The new rulers introduced a feudal approach to governing England, eradicating the practice of slavery but creating a much wider body of unfree labourers called serfs. The position of women in society changed as laws regarding land and lordship shifted. England's population more than doubled during the 12th and 13th centuries, fuelling an expansion of the towns, cities and trade, helped by warmer temperatures across Northern Europe. A new wave of monasteries and friaries were establ