Roger I of Tosny Fécamp Abbey were installed. This monastery was one of the first baronial foundations in Normandy The foundation charter reveals that the lord of Tosny gave it a small possession around Conches and his forest. In 1035, Robert I's death began a troubled period in the duchy of Normandy. Civil wars multiplied and Roger (whose relations with his neighbours was already argumentative) was one of the main players in them. According to the Norman chroniclers, the lord of Tosny refused to serve the new duke, the future William the Conqueror, due to his being a bastard. He especially took advantage of
William, Duke of Brunswick the ruling duke permanently. William left most government business to his ministers, and he spent most of his time outside of his state at his possessions in Oels. While William joined the Prussian-led North German Confederation in 1866, his relationship to Prussia was strained, since Prussia refused to recognize Ernest Augustus, Crown Prince of Hanover, his nearest male-line relative, as his heir, because of the Duke of Cumberland's claim to the throne of Hanover. William died in 1884; he passed on his private possessions to the Duke of Cumberland. His death caused a constitutional crisis for Brunswick that lasted until