Perhaps the second thing about this expedition into the Southwest that's intriguing is that hardly anyone's ever heard of it. And there's a really good reason for that.
This expedition was not, as Jefferson himself put it to Congress in 1807, nearly so successful as that of Lewis and Clark. The reasons why it wasn't successful have to do with the diplomatic tangle of the times, and with the fact that Jefferson launched this expedition into a part of the West that was a lot more accessible to other European powers than the Lewis and Clark expedition up the Missouri ever was. Because it was aimed at the Red River, and hopefully the Arkansas River as well, a Southwestern expedition would lead Jefferson's explorers onto the boundaries of Spanish territory—in fact, within a hundred miles of the nearest Spanish presidios and missions, in what is now Texas.
And the fact that this expedition, as Jefferson planned it, was going to graze, or even penetrate, Spanish territory, made it possible for the Spaniards to react to it in a way that they couldn't react to Lewis and Clark. They hoped to stop Lewis and Clark on a number of occasions. They were never able successfully to do so, but Spain, in the case of this Southwestern expedition, was able to send out an expedition to stop it.