The obvious antidote to a barbarian horde is a bevy of butlers. (We're not sure about the venery for butlers as they tend to be singular.)
[In my dream last night, the castle chatelaine did not care who, actually, controlled the castle, only that the proper procedures were met. I imagined him having to tell a barbarian conqueror, "Sorry, but until you learn some decorum, I cannot allow you within my keep."]