Why were colonies a benefit to the Imperialist powers?
There were three main reasons why colonies benefitted the imperial powers (or why those imperial powers thought colonies helped them). One of these reasons was economic, one was political, and one was military.
Powerful countries took colonies partly because they felt those countries would help them economically. There were two ways in which colonies could help. First, colonies could serve as places to get raw materials. Industrialized countries needed raw materials and colonies were places where they could get those resources without having to buy them. Second, colonies could be markets for the imperial powers. Industrialized countries could produce large amounts of goods. They had to sell those goods somewhere and they felt that colonies made good “captive markets” in which to sell. In these two ways, colonies could benefit imperial countries economically.
The political and military benefits of colonies were closely related. Militarily, colonies could help a country project its power around the world. For example, US naval bases in Hawaii and the Philippines were seen as a way that American power could extend into Asia. Ships from those bases could intervene relatively quickly in anything that happened in Asia and the Pacific. This kind of military power helped bring political power as well. A country with colonies had political power because it was militarily strong and also because of the prestige of having colonies. Colonies, then, could help an imperial power have more power and could help it to seem more important in international politics.
Thus, we can see that imperial powers got military, political, and economic benefits from having colonies.
Imperialist powers wanted colonies for a number of reasons. First, the colonies were a source of raw materials for their mother nations; these materials were particularly needed during the Industrial Revolution in Europe and the United States. For example, the Belgians held the Congo for the purposes of extracting ivory and, later, rubber. In the process, the Belgians in the Congo abused and brutalized the local people. In addition, imperialist nations wanted colonies as markets for their manufactured goods.
Colonies were also of military benefit to their home countries. The British held a number of naval stations abroad, and the United States, influenced by Alfred Thayer Mahan's book The Influence of Sea Power Upon History, acquired naval bases in the Philippines, Cuba, Hawaii, and elsewhere to bolster its military power around the world.
Finally, colonies could provide career opportunities for people in the home country; for example, many British people were employed by their government's bureaucracy in India and elsewhere.