One can hardly imagine a better brief description of our national history than Frost's image of "the land vaguely realizing westward." Both "vaguely" and "realizing" are unexpected, and perfect. The poet gets the haphazard, unplanned quality of the process in the former term and underscores the seeming historic inevitability of it in the latter; in Frost's version of social Darwinism, morality is stripped to the bare essentials: there were millions of strong transplanted Europeans in the East, and they would eventually need room to expand; they had greater numbers and better weapons than the native people, so they overcame them; indeed, they nearly wiped them out altogether! That they remained "unstoried, artless, unenhanced" is also part of the story, and Frost does not (as a lesser, merely patriotic poet might have done) overly praise these conquerors, who even seem more like a virus than a nation.
From Robert Frost: A Life. Copyright © 1999 by Jay Parini.