Given the period of westward expansion from 1812 to 1860, analyze the role of war and power politics in tempering the "virtuous" drive of

Given the period of westward expansion from 1812 to 1860, analyze the role of war and power politics in tempering the "virtuous" drive of "Continentalism" as our borders formed, and again with a new chapter with different purpose at end of the 19th Century.