But in any case, as Jefferson had instructed them, they proceeded upriver with Caddo guides, and for about an additional three weeks, until, in fact, the date of July the 29th, 1806, the Freeman and Custis Expedition explored up the Red River through what is now northwestern Louisiana, southwestern Arkansas, the northeastern corner of Texas, and they had almost reached the eastern border of what is now Oklahoma, when they rounded a bend in the river and were confronted by the sight of a Spanish army four times their size, arrayed in a position across the river.
Freeman, at this point, consulted his orders, consulted with Captain Richard Sparks, who arrayed the Expedition into a defensive posture. And for two days these two opposing forces, the Americans with their eyes on the American West and the future of the West, and the Spaniards, who represented sort of a crumbling empire in the American west, that was actually into its last decades…its last two decades…of enjoying any kind of sovereignty in that part of the world—eyed one another on the Red River while Captain Viana of the Spanish force, and Freeman and Captain Sparks of the American force, had two days worth of parleys. Viana was polite, but he was firm.
He said, my instructions are, you cannot proceed beyond this point. He said, this is as far as the French ever established settlements and posts the Americans had passed an old French post about two days before. And the Spaniards had set up their blockade of the river just about fifty miles upstream of that old French post, and Viana said, this is as far as the French ever proceeded on the Red River, the country above this is ours, and you are going to have to retrograde to American territory.
Freeman no doubt looked at Jefferson's letter of exploring instructions, and read that paragraph where Jefferson told him, If confronted by a superior force, we want you to turn around, and bring back whatever information you have. And so after two days of considering his situation, Freeman decided to turn around.
And so the Expedition had met "the other" in the Southwest, and ended up turning around and proceeding back downriver. That was the fate of Jefferson's Southwestern Expedition. It confronted Spanish-Americans who were determined not to let it explore into their territory, and it was forced to retrograde.
The outcome of the Expedition led to what almost was a war between the United States and Spain. Two opposing armies in fact confronted one another in the territory between Texas and Louisiana in the summer of 1806. They ended up finally signing the Neutral Ground Agreement of 1806, which established a neutral ground between Spanish and American possessions on the southern border of Louisiana Territory. And that situation prevailed until 1819, when the Adams-Onis Treaty finally established a boundary between the two powers.
The Adams-Onis Treaty, by the way, included the Red River as the boundary between Spanish Texas and American Louisiana.
Custis was, you'll recall, in the medical program at the University of Pennsylvania. He went back to the University of Pennsylvania, got his M.D. degree in 1807, so he was the physician. He was a trained…and after 1807 he was Doctor Custis.