The Viking William Longsword conquered the Cotemtin Peninsula from the Franks, thereby creating the area we now know as Normandy.

It started when his father, Viking leader Hrolfur (or Rollo as the Franks called him) negotiated with the Frankish King Charles the Simple in 911 to cease conducting raids in the Seine in return for land around Rouen. Hrolfur established the settlement but eventually returned to raiding.

His son, William Longsword, assumed leadership of the Seine Vikings when his father died in 927 and launched the campaign which was to form the French Province of Normandy.

William the Conqueror, a descendant of William Longsword, was later to conquer Britain, and so we can say that the current British royal family is descendant from Vikings!