William the Conqueror ruled Normandy before invading England in 1066. He became Duke of Normandy in 1035, when he was still a child, after the death of his father, Robert the Magnificent.
William’s early rule was contested by powerful Norman nobles, and he spent years fighting to strengthen his authority over the duchy. Normandy was a strategically important territory on the northern French coast, with close political, cultural and family links to England. William himself was related to the English royal family through his aunt Emma of Normandy, the mother of Edward the Confessor.
After Edward’s death, William claimed that Edward had promised him the English throne. Harold Godwinson was crowned instead, so William assembled an army and crossed the Channel. His victory at the Battle of Hastings made him King William I of England, although he continued to rule Normandy as well. Normandy should not be confused with Brittany or Aquitaine, which were separate regions with different political histories.