EQ: What motivated imperialism, and why did it boom in the late 1800s and not earlier?
Generally, it was mostly the desire for power or advantages over other nations that drove imperialism. The economic justifications show that countries wanted to become richer, which would give them an advantage over other nations since they would have more resources to spend on different things like the military. The political motives also show that each nation wanted to have certain advantages over other countries since some colonies were in strategic locations and allowed the colonising country to have control over waterways and trade routes.
Imperial expansion boomed in the 1800s and not earlier because of the Industrial Revolution. Technology advanced and therefore gave the European nations technological advantages over the African countries. Steam powered ships, guns, and better technology in general allowed them to successfully defeat the other nations. It was probably because of the fact that the European countries had more advanced technology that they thought they would bring "civilization" to the colonies. It hadn't happened earlier because there was not a significant gap between the technologies and therefore Europe had very little advantage over the African countries.