New principalities always cause problems for the prince. People are willing to change rulers to better their own lot, but they soon discover that things have gotten worse, because a new ruler must harm those he conquers. Then you have as enemies those you harmed while seizing power, as well as those who put you in power, because you can never satisfy all of their ambitions.
If conquered territories annexed to yours are similar in location and customs, it is easy to keep them, especially if they were hereditary principalities not used to independence. As long as you do not change their way of life, you need only wipe out the old ruling family to keep them.
But if new territories are different in language and customs, they are difficult to keep. The best methods are to go and live there yourself, to establish colonies in them, to protect the neighboring minor powers, to weaken strong factions within the state, and to guard against foreign powers. It is important to deal with developing political problems early, rather than wait until it is too late, because wars can never be avoided, only postponed. King Louis did not follow these policies in Italy and therefore failed to keep his territories. He also erred by making the Church more powerful, because to make others powerful is to weaken yourself.
