Viking advances were allowed to escalate, and their dreaded longboats were sailing up the Loire and Seine Rivers and other inland waterways, wreaking havoc and spreading terror. In 843 Viking invaders murdered the Bishop of Nantes, and a few years after that, they burned the Church of Saint Martin at Tours, and in 845 the Vikings sacked Paris. During the reign of Charles the Simple (898–922), Normans under Rollo were settled in an area on either side of the Seine River, downstream from Paris, that was to become Normandy.