Answer: Pathos
An appeal to pathos is one that tries to elicit emotional responses from the listener in order to persuade him of a particular opinion. In this sentence, the author is criticising someone who has brought American Indians to their frontiers. The depiction of these Indians is full of words with negative connotations, such as "merciless" and "savages." Moreover, the speaker paints a picture of the American Indians killing everyone they see, regardless of age, sex and condition. This description is meant to encourage an averse feeling towards Indians, and support for the speaker's cause.
