Actually the Normans were really descendants of the Vikings or Norseman...thus Normans who were granted or gifted land in Northern France ie Normandy as a bribe to stop them causing trouble, if you watch the series Vikings it is getting to the point where they attacked Paris, so the series is pretty accurate so far, they had already been raiding Britain for a while and were granted/gifted certain parts of the country to settle in, as in France, to stop them causing more havoc....of course The Battle of Hastings was much later than this but that is how Norsemen became Normans, so really it was Vikings descendants attacking Vikings descendants at Agincourt.....grrr fucking Viking troublemakers lol.