In 1845, political journalist John O'Sullivan had merged American's nationalism and needed to expand westward to devise the term "manifest destiny". The term is defined as the belief that westward expansion was the God-given right of Americans, even their duty, to expand U.S. territory all the way to the western coast of the Pacific Ocean. This provided an "ideological shield for westward expansion", masking the selfish and pompous motivations behind those who advocated it. This philosophy was extremely damaging to several parties who found themselves in the path of the hordes of American migrants, yet Americans believed it was their destiny to expand their nation across the entire continent. .
In order to fulfill their manifest destiny, Americans believed they had the right to resist and retaliate against any foreign power that stood in their way of westward expansion. Our nation's ancestors believed that the American culture of white supremacy gave them the entitlement to dominate and seize any territories held by other foreign powers; considering their democratic lifestyles better than any other in the world. Although the outcome of our nation's manifest destiny expanded the United States drastically, it left American's blind to the injustice of it. .
Americans believed so strongly in this philosophy because it was an acceptable ideal that justified their need to migrate west. American's motivations to migrate and expand west included land hunger, reform movements, and religious reasons. In the 1840's and 1850's, the "free labor" ideal had embedded a new self-made work ethic in American society, centered on self-sufficiency, independence, and hard work. The free labor ideal caused economic equality throughout the country. Competition amongst Americans, as well as amongst the large amounts of poor Irish farmers and skilled German immigrants into the country, was at an all-time high.