A fierce and successful Viking raider, he plundered the French coast for several years, after which he was offered permanent territory if he would cease his raids and protect the helpless coastal communities fending off other Viking raiders. Rollo and his followers prospered on this conceded land of Normandy.

Following Rollo's death in 930, his son William Longsword continued family dominance over the territory. Over time, the Norman numbers grew and they expanded rule to include England, Southern Italy and Sicily.