His career is interesting for several reasons. The charters he received from King Stephen and Empress Matilda illustrate the ambitions of English barons. The most important concessions are grants of offices and jurisdictions, which had the effect of making Mandeville almost a viceroy with full powers in Essex and Hertfordshire, Middlesex and London, but these were based on offices and jurisdictions his ancestors had held. His career as an outlaw exemplifies the worst excesses of the civil wars of 1140–1147, and it is possible that the deeds of Mandeville inspired the rhetorical description of this period in the "Peterborough Chronicle", when "men said openly that Christ and his saints were asleep." He had seized Ramsey Abbey (near Peterborough) in 1143, expelling the monks and using Ramsey as a base for forays into the surrounding region, sacking Cambridge and other smaller settlements.