The Arbella was not a ship of colonists but a vessel of theology. In 1630, before its passengers set foot on the Massachusetts shore, Puritan lawyer John Winthrop framed their mission not as migration but as cosmic destiny. “We shall be as a city upon a hill,” he declared. “The eyes of all people are upon us.” This was a charge for exemplary isolation, a demand for moral purity so radiant it would reform a corrupt Europe from across an ocean. It contained no plan for territorial conquest. Yet, within this image lay the dormant DNA of an empire: a belief in a unique, providential mandate and a sense of righteous separation from a fallen world.
This spiritual covenant would be secularized, weaponized, and stretched across a continent. The American Revolution transformed the “city” from a Puritan sanctuary into the world’s first modern republic, a political model for mankind. Thomas Jefferson spoke of an “empire for liberty.” The land itself, however, was never empty. The “how” of American expansion—the dispossession of Native nations, the war with Mexico—required a justifying “why.” The answer emerged in 1845, when journalist John L. O’Sullivan, defending the annexation of Texas, coined the perfect secular scripture: “manifest destiny.” It was America’s “manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions.”
The phrase was a masterstroke of ideological fusion. It married Winthrop’s divine providence to Jefferson’s republican liberty and grafted both onto a virulent theory of Anglo-Saxon racial superiority. The continent was not stolen; it was allotted. Its inhabitants were not societies with sovereignty but “savages” obstructing progress. This was not empire-building; it was the fulfillment of a sacred and inevitable historical law. By 1890, the U.S. Census Bureau declared the frontier closed. The mythic engine of American identity had reached the Pacific. A profound national anxiety set in. If the continent was filled, what would become of a people whose sense of purpose was built on expansion? The city upon a hill now needed a new frontier.