"By the terms of the Frontier Myth, once imperial war was conflated with savage war, both sides become subject to the logic of massacre. The savage enemy kills and terrorizes without limit or discrimination in order to exterminate or drive out the civilized race. The civilized race learns to respond in kind, partly from outrage at the atrocities it has suffered, partly from recognition that imitation and mastery of the savages' methods way the best way to defeat them. A cycle of massacre and revenge is thus inaugurated that drives both sides toward a war of extermination. Only an American victory can prevent actual genocide: the savage enemy would indeed exterminate all the civilized race, but the civilized carry massacre only as far as necessary to subjugate the savage. To achieve victory in such a war, Americans are entitled and indeed required to use any and all means, including massacre, terrorism, and torture."
Slotkin, Richard; Gunfighter Nation (1992) p. 112