The Prince Chapter 5
How to govern cities and principalities that, prior to being occupied, lived under their own laws
There are three ways of keeping a principality that is accustomed to living under its own laws: destroy it, reside in it, or allow a form of self-government that is friendly to the prince and take tribute from it. But the only sure way is to destroy it because there is always a chance that its residents will rebel in the name of freedom, which once tasted is never forgotten. Thus, a territory that is used to having a ruler will be easier to control than a more liberal territory, such as a republic.