Salisbury oath
The Salisbury oath of August 1086 to William the Conqueror was part of a fundamental feudal reform in England following the Norman invasion.
After Wilhelm had dissolved the original Anglo-Saxon counties after the conquest of England , he redistributed the land to his Norman followers, who swore the feudal oath to him in Salisbury . They were first subordinated to him and only then possibly to other liege lords ( whosoever's vassals they might be ).