Short answers, pulled from the story.
The Viking leader Rollo signed the treaty on the 14th of October 911 at Saint-Clair-sur-Epte. This agreement granted lands along the river Epte and the Atlantic coast to Rollo and his men in exchange for protection against future raids.
William the Conqueror secured a decisive victory at the Battle of Hastings on the 14th of October 1066. This event led to the conquest of England three years later and replaced the Anglo-Saxons as the ruling class of England.
The Normans expanded into Scotland, Wales, southern Italy, Sicily, the Iberian Peninsula, and North Africa. They established kingdoms in Sicily and conquered cities on the Ifriqiya coast corresponding to modern Tunisia, Algeria, and Libya between 1135 and 1160.
Within a generation the Norman elite abandoned Old Norse for the Gallo-Romance language spoken by their Frankish neighbors. This linguistic fusion created Old Norman which evolved into regional languages including Cotentinais, Cauchois, Jèrriais, and Guernésiais.
The Domesday Book was written in 1086 to formalize land ownership and feudal obligations in England. It established a legal framework for resolving property disputes under a system where all land was held by the king who granted it to nobles in exchange for military service.