William the Conqueror became the first Norman King of England in 1066. His coronation ended in violence when Norman knights mistook cheers inside the abbey as a rebellion and burnt surrounding houses, killing Englishmen. He seized land from defeated Anglo-Saxon nobles and gave it to his Norman knights. When the northern English rebelled, William brutally punished them by burning villages and destroying crops. He finally defeated the Anglo-Saxon leader Hereward the Wake by building a causeway across marshes to access the town of Ely. To ensure loyalty from remaining Anglo-Saxon nobility, William forced them to swear oaths and took their sons as hostages.