The answer is: The Law of Land Warfare, Uniform Code of Military Justice, and Code of Conduct.
The answer may vary from country to country but on an international level the United Nations Charter also provides code of conducts on how modern armies should function in times of war.
These are important in order to provide a moral structure to an Army which can become, as evidenced in history, quite ruthless.
The business opportunity that first brought interested Europeans to the delta of the Niger River was the quick way to trade palm oil and spices.
The Niger River flows from East Africa thru West Africa. The means of transportation during that time was thru the use of boats and vessels from Europe need to stop at the port of the Delta of Niger River to enter deep into the continent.
The civil rights movement was in the 1960's when african americans didn't have the rights of white people.
