Imperialism is defined as an unequal political, economic and cultural relationship. Imperialism does not necessarily involve the political control of new territories (although colonies are often associated with imperial rule) and is based on a need to clearly divide between colonizer and colonized.

First, it was justified by a new civilizing mission. As part of this process, Europeans misapplied scientific ideas to view themselves as the most advanced civilization in the world and created a new hierarchy of races: Asians in the middle, Africans near the bottom, and aborigines at the bottom. Responding to this altruistic desire to assist non-Western people, political activist George Bernard Shaw quipped that the British never admit to wanting something, but develop “a burning conviction that it is his moral and religious duty to conquer those who possess the thing he wants.”

Associated with this civilizing mission was the second factor, a desire to end the “Arab Slave Trade” that exported slaves from central/East Africa to the East African coast, all the while forgetting that Britain was the major slaver of the previous generation. However, the idea that intervention in Africa was needed to save Africa from Africans is one that continues even now in the present.

Third, new nationalist rivalries in Europe pushed European nations to try to claim as much of the world as possible. France avenged its humiliation in the Franco-Prussian War by going to war in Africa and Asia. Japan asserted its new national pride by colonizing East Asia and the Germans colonizing parts of Africa and the Pacific in the name of demanding for greater living space. British crowds cheered the defeat of the South African Boers in 1902. The wars of empires and tales of exotic adventure abroad captured the potentially revolutionary energy of the working class. Fourth, imperial rule was emboldened by an unstable frontier. European traders, missionaries, and settlers worked to push and expand colonial rule, often causing conflicts with Asians and Africans that necessitated the intervention of the colonial state. Often, especially in South Africa, the government in London reacted to events as colonial settlers pushed the frontier inland. This provoked wars that necessitated government intervention against groups such as the Xhosa, who rebelled against colonial rule.

Finally, new technology provided some vital advantages. New inventions, such as the repeating rifle and Maxim gun, armed forces enough to defeat numerically superior enemies. One example is the Anglo-Egyptian conquest of the Sudan in 1896. 10,000 Mahdi soldiers were killed by just 47 British and Egyptian troops with the help of modern machine guns. However, the technological advantage of Europeans was often greatly exaggerated. The near constant resistance to Europeans (see below) which involved the use of European guns demonstrated that those in Africa and Asian enjoyed at least some access to European technology. The use of native soldiers by Europeans provided a more significant advantage to European colonization than taxation. For example, the Indian Army, paid for by Indian taxes, were used in conquering and policing campaigns throughout the world, but especially Chinese, Ethiopian, Egyptian, Sudanese, Burmese and East African theatres of war. Additionally, local fighters also joined imperial armies, hoping to escape poverty, take revenge against traditional enemies, or because of their training/value as warriors. Thus, for a variety of reasons but justified by the civilizing mission, Western Europeans began a new wave of expanding abroad and began furthering gaps measured in terms of overall wealth, living standards, and life expectancy.