Battle of Hastings
Fought on the 14th October 1066 between the Anglo-Saxons and the Normans. The Normans were actually Vikings who had settled in France, so we weren't actually invaded by the French. That would have been a horror too great to countenance. The Normans were led by William the Bastard. (the Conqueror bit of his name came later).
Happened at the village of Battle near Hastings. Now what are the odds on that, eh?
Victory came to William because a Norman unit retired from combat for a rest and the 'English' forgot it was Vikings they faced and not Frogs. Several parts of the English shield wall thought they were fleeing, pursued and got shoed in the open. Then it was all over but the pursuit and massacre.
This link, if a little poncy in it's tone, contains more info.
This wiki page is probably better for a view of the battle.