In his biography of Charlemagne, historian Richard Winston advanced the idea of sanctuary and similar privileges being granted to the clergy to give them a usef

In his biography of Charlemagne, historian Richard Winston advanced the idea of sanctuary and similar privileges being granted to the clergy to give them a useful function to native Pagan populations (Frankish -- modern day France and Germany) that would otherwise be hostile to clergy. Charlemagne also used monks and priests in something that looks like a proto-civil service role... the registry of births, deaths, sacraments (marriage, etc) could be used for taxation, sorting out property, etc. It's an interesting book. Charlemagne comes across as very realpolitik-ish despite the outward shows of piety, and also an excellent administrator.