Viking leader who founded the duchy of Normandy (d. c928). Although regarded in Norman sources as a Dane, Rollo was probably Norwegian: late Icelandic sources identify him with Gongu-Hrolf, a son of Rognvald of More, who turned to piracy after he was outlawed by Harald Fairhair. According to the Norman chronicler Dudo of St Quentin, Rollo arrived on the Seine in 876. In 911 he led a band of Danish Vikings in an unsuccessful attack on Chartres. In peace talks at St-Claire-Sur-Epte, king Charles the Simple of the West Franks granted Rollo the county of Rouen and other districts on the lower Seine in return for his homage and defence of the area against other Viking raiders. Rollo was baptised in 912, though he did not give up worshipping the pagan gods. Rollo was granted further territories around Bayeux in 924, but broke the treaty in 925, attacking Amiens, Arras and Noyon, before he was defeated at Eux by the counts of Flanders and Vermandois. Rollo was succeeded by his son William Longsword.
Notes from Encyclopaedia of the Viking Age by John Haywood. Thames
& Hudson 2000. pp 160.