There have been countless conquests in human history and many huge empires created from them. The methods of conquest have evolved through the years creating advanced forms of conquest which cost the conqueror less and earn them more. One of the most advanced forms is the cultural conquest, in which the culture of the conquerer is adopted by a people of the disputed territory, eventually to the point where they adopt a sense of nationalism for a country which is not their own. This sort of sympathetic nationalism can, on its own or with some encouragement from the conqueror, lead to popular demands for annexation or even open rebellion.
This form of conquest can be carried out with little or no risk to the conqueror. There is no need for the conqueror to risk its own military or resources, and there is very little cost to the conqueror in the world political arena. After all, how can the conqueror be expected to calm the hearts of a foreign people? Furthermore, if things go very poorly, for instance, if the rebels commit egregious war crimes and brutal acts, the conqueror can easily turn its back on them, leaving them to fend for themselves against the world. The next concern is interference from other world powers. If another world power involves itself, then the conqueror can claim that the whole thing was something that just happenned to them, and the interferer can be made to look like a meddler in other people’s business or an imperialist in its own right. With these things considered, cultural conquest carries no real risk to the conqueror.
As for the reward, the conqueror gets a chance to absorb any natural resources of the disputed territory and expand its influence over the people. To maximize this benefit and minimize risk, the conqueror would theoretically prefer that the territory rebelled against its current leadership. They would not desire peaceful annexation because it brings the new territory and people into the empire at full strength, which can make them a threat to one or more of any existing competing political parties. If the new people lean towards one party over another, than the other party would strongly oppose the annexation, and If the annexation occurred anyway, they’d fight to limit the new people’s rights and power in the existing government. Such a limitation of rights must inevitably result in dissatisfaction of the people in the new territory, which greatly reduces its value to the conqueror. On the other hand, if territory were encouraged to rebel against their current government, then they would suffer all of the expected infrastructure and human cost of war. Such that, if they won the rebellion, and then were annexed, they would enter the empire in a greatly weakened state. The existing political parties would not be threatened, and would actually compete to win over the new territory, possibly by proposing various reconstruction programs or veteran assisstance. Thus it is often in the conquerors’ best interest to foment rebellion then to attempt to annex an intact territory.
From all this we can conclude that cultural conquest is nearly risk free for the conqueror and can have great benefits. But in practice it often involves a rebellion or civil war of some sort that comes at a human cost. In the interests of world peace, cultural conquests should be discouraged or in some way prevented wherever possible. This, however, is a lofty goal. As I’ve already stated interfering in an ongoing cultural conquest can be very costly to the interferer in the form of money, world opinion, and even the lives of armed forces. Thus, the problem can only be effectively dealt with by prevention, which can be exceedingly difficult and costly for the nation which owns the disputed territory. Obviously, punishment of the disputed territory would only encourage rebellion, which leaves the proverbial carrot. The carrot often consists of a combination of nationalist propaganda and infrastructure spending. The big problem with the carrot is that if it doesn’t work, then all of that money would have been spent for nothing. It can be a very high risk for the owner nation of the territory. I’m not sure if there is a reliable way to combat one of these cultural conquests other than to maintain a strong sense of nationalism at all times, and that is something which can be a problem for any nation, and nationalism can have some serious drawbacks as well (as with any -ism).