CH 12 Medieval Europe/Evolution of Feudal Europe
Starting with William, Duke of Normandy, (AKA William the Conqueror) there was a long line Norman kings that would lead and rule over England. During this time there was a mixing of Anglo-Saxon and Norman French language and cultures. This is part of why the English language makes no sense. To deal with the fact that the king of France was still trying to claim England as part of his land, William had his vassals swear loyalty to him first and other people second. This made it so that in the event that the French king wanted to try to enforce his claim, William could yell, "bring it!" and be relatively sure that none of his nobles would stab him in the back. I'm looking at you Cassius.