Machiavelli
The Prince

The Prince 4: The kingdom of Darius The Prince TOC The Prince 5: New Dominions Conquored by Arms 

5 The Way to Govern Cities or Dominions That,
Previous to Being Occupied, Lived Under Their Own Laws

When those states which have been acquired are accustomed to live at liberty under their own laws, there are three ways of holding them. The first is to despoil them; the second is to go and live there in person; the third is to allow them to live under their own laws, taking tribute of them, and creating within the country a government composed of a few who will keep it friendly to you. Because this government, being created by the prince, knows that it cannot exist without his friendship and protection, and will do all it can to keep them. What is more, a city used to liberty can be more easily held by means of its citizens than in any other way, if you wish to preserve it.

There is the example of the Spartans and the Romans. The Spartans held Athens and Thebes by creating within them a government of a few; nevertheless they lost them. The Romans, in order to hold Capua, Carthage, and Numantia, ravaged them, but did not lose them. They wanted to hold Greece in almost the same way as the Spartans held it, leaving it free and under its own laws, but they did not succeed; so that they were compelled to lay waste many cities in that province in order to keep it, because in truth there is no sure method of holding them except by despoiling them. And whoever becomes the ruler of a free city and does not destroy it, can expect to be destroyed by it, for it can always find a motive for rebellion in the name of liberty and of its ancient usages, which are forgotten neither by lapse of time nor by benefits received; and whatever one does or provides, so long as the inhabitants are not separated or dispersed, they do not forget that name and those usages, but appeal to them at once in every emergency, as did Pisa after so many years held in servitude by the Florentines. But when cities or provinces have been accustomed to live under a prince, and the family of that prince is extinguished, being on the one hand used to obey, and on the other not having their old prince, they cannot unite in choosing one from among themselves, and they do not know how to live in freedom, so that they are slower to take arms, and a prince can win them over with greater facility and establish himself securely. But in republics there is greater life, greater hatred, and more desire for vengeance; they do not and cannot cast aside the memory of their ancient liberty, so that the surest way is either to lay them waste or reside in them.