The importance of the Louisiana Purchase in the history of the United States has become increasingly clear in the century that has just elapsed, and as the nation goes on to fulfill its destiny on the Pacific and in South America it will turn to this event with growing appreciation of the significance of the march across the Mississippi, and the acquisition of the strategic point where the great river enters the Gulf of Mexico. If the Declaration of Independence marks our separation from the colonial system of the Old World, the Louisiana Purchase was the turning-point in the events that fixed our position as the arbiter of the New World.
It is the purpose of these papers to show that this important event was no sudden or unrelated episode in our history. It was the dramatic culmination of a long struggle that began with the rivalry of Spain, France, and England for the Mississippi Valley in the colonial era, continued during the American Revolution, and brought grave problems before the first three Presidents of the United States in the period when Europe was engaged in the contests of the French Revolution.
Although the revisions of the map of Europe, in that era, largely occupied the European diplomats, their archives reveal the fact that the future of the Mississippi Valley received serious attention, and constituted an important element in their policy. When we consider the power which the interior of the United States now exerts over the economic and political welfare of the world, we realize that the diplomatic intrigues for the possession of the Mississippi, the Ohio, and the Great Lakes were of higher significance in world history than many of the European incidents which have received more attention.
Not simply Louisiana was at stake: the whole Mississippi Valley,—the land between the Alleghanies and the Mississippi, as well as the territory across the river,—with the Gulf of Mexico at one end and the Great Lakes at the other, was the prize of the diplomatic game. Indeed, all South America became involved in the designs of the European rivals. For the United States the matter was a vital one. The acquisition of these regions laid the physical foundation for our national greatness, furnished the base from which to extend our power to the Pacific Ocean, and gave us a dominating strategic position in reference to Spanish America. More immediately it put an end to the plans to which France and England had given their attention for forming an interior dependency in the Mississippi Valley, whose sea power should control the Gulf of Mexico, and, by consequence, preside over the division of the decaying empire of Spain in the New World. The Monroe Doctrine would have been impossible if the designs of either France, Spain, or England, during the decade that followed Washington's inauguration, could have been carried out.
At the close of the war for independence the United States held hardly more than the Atlantic coast. Beyond the Alleghanies an advance column of pioneers had pushed a wedge of sparse settlement along the southern tributaries of the Ohio into Kentucky and Tennessee. Ambitious to conquer though they were, their hold was a precarious one. On their right flank lay the basin of the Great Lakes, occupied by warlike Indians held under control by the posts of England at Detroit and at other strategic points on the lakes. In spite of the treaty of 1783, Great Britain retained these posts, the centres of Indian trade and influence, alleging the failure of the United States to carry out certain provisions of the treaty, and expecting that a speedy dissolution of the feeble confederation would leave to her the control of the Great Lakes and the upper Mississippi; nor did she forget her former possessions on the Gulf of Mexico.
On the left flank, controlling the basin of the Gulf of Mexico, were the four powerful tribes of the Southern Indians. Spain held the mouth of the Mississippi at New Orleans, and from Mobile, St. Marks and Pensacola furnished these tribes with goods, arms, and ammunition. In the spring of 1784 the governor of Louisiana, acting on the theory that the savages were independent nations, made treaties which bound them to accept Spanish protection, and, in return, promised to secure them in the possession of their lands. Nor did Spain stop with insuring her predominance among the Indians. She avoided a treaty with the United States at the close of the Revolution. Refusing to be bound by England's cession to the United States, she set up the claim that her victories over Great Britain in the Revolution had given her the right to Florida with the most extensive boundary which England had given to West Florida during her occupation. She also contended that the eastern bank of the Mississippi was hers, finding justification for this in the fact that England, by the Proclamation of 1763, had made crown lands of the colonial territory beyond the Alleghanies, and had forbidden the colonists to settle there. Thus, she argued, her victories over England on the Mississippi and in Florida gave her a sphere of influence in the lands between the Gulf, the Mississippi, and the Alleghanies, at least as far north as the mouth of the Ohio. She further asserted, as the fundamental element in her policy, the exclusive control of the navigation of the Mississippi, which England had promised us by the treaty.