The contrary happens in kingdoms governed like that of France, because one can easily enter there by gaining over some baron of the kingdom, for one always finds malcontents and such as desire a change. Such men, for the reasons given, can open the way into the state and render the victory easy; but if you wish to hold it afterwards, you meet with infinite difficulties, both from those who have assisted you and from those you have crushed. Nor is it enough for you to have exterminated the family of the prince, because the lords that remain make themselves the heads of fresh movements against you, and as you are unable either to satisfy or exterminate them, that state is lost whenever time brings the opportunity.
Now if you will consider what was the nature of the government of Darius, you will find it similar to the kingdom of the Turk, and therefore it was only necessary for Alexander, first to overthrow him in the field, and then to take the country from him. After which victory, Darius being killed, the state remained secure to Alexander, for the above reasons. And if his successors had been united they would have enjoyed it securely and at their ease, for there were no tumults raised in the kingdom except those they provoked themselves.
But it is impossible to hold with such tranquillity states constituted like that of France. Hence arose those frequent rebellions against the Romans in Spain, France, and Greece, owing to the many principalities there were in these states, of which, as long as the memory of them endured, the Romans always held an insecure possession; but with the power and long continuance of the empire the memory of them passed away, and the Romans then became secure possessors. And when fighting afterwards amongst themselves, each one was able to attach to himself his own parts of the country, according to the authority he had assumed there; and the family of the former lord being exterminated, none other than the Romans were acknowledged.
When these things are remembered no one will marvel at the ease with which Alexander held the Empire of Asia, or at the difficulties which others have had to keep an acquisition, such as Pyrrhus and many more; this is not occasioned by the little or abundance of ability in the conqueror, but by the want of uniformity in the subject state.
Whenever those states which have been acquired as stated have been accustomed to live under their own laws and in freedom, there are three courses for those who wish to hold them: the first is to ruin them, the next is to reside there in person, the third is to permit them to live under their own laws, drawing a tribute, and establishing within it an oligarchy which will keep it friendly to you. Because such a government, being created by the prince, knows that it cannot stand without his friendship and interest, and does it utmost to support him; and therefore he who would keep a city accustomed to freedom will hold it more easily by the means of its own citizens than in any other way.