The soldier had won the back country for the new nation. Could the diplomat hold it? As early as March 19, 1779,--just three weeks after Clark's capture of Vincennes,--the Continental Congress formally laid claim to the whole of the Northwest; and a few months later John Adams was instructed to negotiate for peace on the understanding that the country's northern and western boundaries were to be the line of the Great Lakes and the Mississippi. When, in 1781, Franklin, Jefferson, Jay, and Laurens were appointed to assist Adams in the negotiation, the new Congress of the Confederation stated that the earlier instructions on boundaries represented its "desires and expectations."
It might have been supposed that if Great Britain could be brought to accept these terms there would be no further difficulty. But obstacles arose from other directions. France had entered the war for her own reasons, and looked with decidedly more satisfaction on the defeat of Great Britain than on the prospect of a new and powerful nation in the Western Hemisphere. Furthermore, she was in close alliance with Spain; and Spain had no sympathy whatever with the American cause as such. At all events, she did not want the United States for a neighbor on the Mississippi.
The American commissioners were under instructions to make no peace without consulting France. But when, in the spring of 1782, Jay came upon the scene of the negotiations at Paris, he demurred. He had been for some time in Spain, and he carried to Paris not only a keen contempt for the Spanish people and Spanish politics, but a strong suspicion that Spain was using her influence to keep the United States from getting the territory between the Lakes and the Ohio. France soon fell under similar suspicion, for she was under obligations, as everyone knew, to satisfy Spain; and little time elapsed before the penetrating American diplomat was semiofficially assured that his suspicions in both directions were well founded.
The mainspring of Spanish policy was the desire to make the Gulf of Mexico a closed sea, under exclusive Spanish control. This plan would be frustrated if the Americans acquired an outlet on the Gulf; furthermore, it would be jeopardized if they retained control on the upper Mississippi. Hence, the States must be kept back from the great river; safety dictated that they be confined to the region east of the Appalachians.