<span>Manifest Destiny is a nineteenth-century belief that the United States had a mission to expand westward across the North American continent, spreading its form of democracy, freedom, and culture. The expansion was deemed to be not only good, but also obvious ("manifest") and certain ("destiny"). </span>
Answer : Mercenaries would fight if they were paid not for their country and sometimes they would turn against the Empire that paid them.
Um... isn't that the answer? you just put it in the question. it's not a question.