Monroe proclaimed that the New World, the Western Hemisphere, was closed to further colonization; and that any attempt by the European powers of the Old World, whether Portugal and Spain diminished powers in the south to recolonize or Britain and France in the North to newly colonize  would be viewed as acts of hostility.

Yet America’s self-appointed role as protector in the region, and the countries just mentioned, against European expansion was only made possible by the Louisiana Purchase. That is to say the acquisition of mainly swampland owned at the time by France running the entire length of the Mississippi river to the East taking in all its tributaries stretching westwards as far was what was then called New Spain.