The effect of bringing political unity to the Mississippi Valley by the Louisiana Purchase was profound. It was the decisive step of the United States on an independent career as a world power, free from entangling foreign alliances. The victories of Harrison in the Northwest, in the War of 1812 that followed, ensured our expansion in the northern half of the Valley. Jackson's triumphal march to the Gulf and his defense of New Orleans in the same war won the basis for that Cotton Kingdom, so important in the economic life of the nation and so pregnant with the issue of slavery.[189:1] The acquisition of Florida, Texas, and the Far West followed naturally. Not only was the nation set on an independent path in foreign relations; its political system was revolutionized, for the Mississippi Valley now opened the way for adding State after State, swamping the New England section and its Federalism. The doctrine of strict construction had received a fatal blow at the hands of its own prophet. The old conception of historic sovereign States, makers of a federation, was shattered by this vast addition of raw material for an indefinite number of parallelograms called States, nursed through a Territorial period by the Federal government, admitted under conditions, and animated by national rather than by State patriotism. The area of the nation had been so enlarged and the development of the internal resources so promoted, by the acquisition of the whole course of the mighty river, its tributaries and its outlet, that the Atlantic coast soon turned its economic energies from the sea to the interior. Cities and sections began to struggle for ascendancy over its industrial life. A real national activity, a genuine American culture began. The vast spaces, the huge natural resources, of the Valley demanded exploitation and population. Later there came the tide of foreign immigration which has risen so steadily that it has made a composite American people whose amalgamation is destined to produce a new national stock.