nearly levelling Rouen and other settlements. Eventually, he conceded "certain coastal provinces" to them. Although, scholars have debated this and have said that Rollo did not even arrive in West Francia until after the year 876, making this timeline given by Dudo wrong.

According to Dudo, Rollo struck up a friendship in England with a king called "Alstem". This has puzzled many historians, but recently this person has been identified as Guthrum, the Danish leader