"Manifest destiny" was the term coined by John O' Sullivan in the mid- 1800's; he was writing about his belief, shared by many, that the United States was destined by none other than God himself to expand from the Atlantic Ocean all the way to the Pacific, implementing democracy in very corner of the continent, regardless of who might be in the way. This term caught the imagination of many Americans at a time when the United States was eyeing the British-controlled Oregon Territory in the Northwest, and O' Sullivan stated, among other things, that since Britain would not be implementing democracy in the territory, the nation did not have a valid claim to it.
“Manifest destiny” was first used by John O’Sullivan in an article in an 1845 issue of the United States Magazine and Democratic Review . While manifest destiny was more concept rather than policy, it was the belief that the United States was destined to expand across the North America to the Pacific Ocean. It was seen that the United States and its superior form of government was “divinely” favored and should expand. “Manifest destiny” was used to justify war with Mexico in the 1840’s and annex Texas. It was also used to acquire the Oregon territories from Great Britain. It was not a call to obtain territory by force but belief that Anglo-Saxons would move into these new areas and set up new republican governments in turn seeking admission to the United States.
Manifest Destiny was the belief that the U.S. was destined to secure territory from "sea to sea," from the Atlantic to the Pacific Ocean. The phrase was coined by New York journalist John L. O'Sullivan.Manifest destiny was first used by John O’Sullivan.