What role did racism have in imperialism?

racism became one of the ideas supporting imperialism. It was linked to other ideas as well (superiority of reason over feeling and sentiment, concept of European powers as racional and naturally progressive, idea of progress as a typically European idea, equation reason = progress). Other races were usually (in the best case) infantilized or barbarized. Behind all that was a belief that there is a historical law (inevitability) of European whites being a dominant race bringing others to rationality, civilization, progress. All that made imperialism much more powerful. It led to conviction that the imperialism is inevitable historical law.

Explanation:racism as scienfific doctrine (biological determinism resulting in cultural relativism) is a product of 19th-century thought inspired by Darwin and leading to social Darwinism of Herbert Spencer, Ernst Haeckel and others. But already in 18th century there was a belief (it means rather philosophical perspective and attitude than scientific theory) that certain races are made of inferior material (idea quite common between men of Enlightenment like Thomas Jefferson).

after the civil war, and with the termination of slavery, the south was faced with a big problem; what was supposed to happen and how they were supposed to deal with the freedom and the rights that black people and freed slaves had gained as a result of the north defeating the south and forcing the end of slavery. first, most, if not all, of the workforce of the south came from slaves and they did not have an option to replace the loss of said workforce. second, particularly in the south, people were convinced that black people were lesser, less intelligent, less capable and less smart than whites. this posed a huge problem for them. also, southerners were faced with another issue; freed slaves now had a say in how their lives would be lived and the right to politically choose the way they would be governed. people in the south did not want to accept this, none of this and this opposition and the conflicts that arose from it, not to mention the afereffects of the war, forced the congress of the time to enact and enforce the reconstruction plans that had been proposed by president andrew johnson.

c) troops march forward in close formation against newer, more accurate weapons