OK, if we limit it to those very narrow terms, I can somewhat agree to that, with the caveat that all of that happened before and without Darwin and continued after publication of his book.
Conquest has been the way of humans since one had something the other wanted that they did not want to part with.
Phrases like: 'Utilizing what those backward savages never would' became scientifically justifiable on another level when those 'backward savages' were considered evolutionarily inferior and thus less than human, therefore not deserving of the Rights and respect humans were. In effect, it laid philosophical/scientific groundwork for considering those targeted populations lesser beings or even as animals.
With science in hand, virtually any act against any "lesser" beings could be justified, from enslavement, to diamond and gold mining/exploitation, to the concentration camps. All that was necessary was to successfully define a group as lesser beings, to dehumanize them, and get people to consider them to be animals or subhumans, OR to claim they were robbing others of their 'rightful place/resources' in the natural order of things. Claiming to 'right that wrong' kept crematoria going for years in Eastern Europe, for just one example.
There is a fine line between the sort of demonization most populations embrace for an enemy in wartime and racism, and sometimes that line disappears when race becomes something easily defined by some social or physical differentiation. Otherwise, the line is between political or language groups, and any 'racial' element is more of a tribal fiction. Essentially: assert 'They are not us', 'They are inferior to us', 'We rightfully deserve their resources, even if we have to kill them for it'. and virtually any war of aggression/conquest can be framed in those terms. Internal dissent seldom stands against such arguments framed with the scientific certainty that those who 'are not us' are 'our inferior', whether your little 'master race' really is or not.
Virtually all else in human conflict is defensive.